78 articles trouvés pour ce sujet.
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Filling a tank using two pipes |
2006-11-11 |
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Tracey pose la question : One pipe can fill a tank in 8 minutes and a second can fill it in 12 minutes. If the tank is empty, how long will it take both pipes to fill it. Stephen La Rocque and Penny Nom lui répond. |
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Working backwards |
2020-06-05 |
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Jill pose la question : Emma has a bunch of grapes (1)/(2 ) of it she gave it to her friend and (3)/(4 ) of the remaining grapes she gave it to Gina. There are 4 grapes remaining. So how many bunch of grapes to begin with? Harley Weston lui répond. |
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A rectangle and a circle |
2017-08-12 |
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Ramzan pose la question : a diagram shows the shape of rectangular framework with length (2x+20)cm and with (y+10)cm . The outline is made of wire . If a circle with diameter 56 cm is to be made from the wire and the area of the rectangle is 420 square centimeter ,find the possible lengths and width of the rectangle Penny Nom lui répond. |
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Filling a pool with two hoses |
2017-02-20 |
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Charlene pose la question : A large hose will fill a pool in 40 minutes while it takes a smaller hose 60 minutes to fill the same pool. The same pool takes 80 minutes to drain if the drain is open. Suppose one day both the hoses are turned on, but by accident the drain was left open. How long would it take to fill the pool that day? Penny Nom lui répond. |
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Working backwards |
2015-08-27 |
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Heather pose la question : Tom took a collection of tiles from a box. Sue took 13 and Bob
took half of those remaining. Tom had 11 left. How many did they start with? Penny Nom lui répond. |
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How many boats total are in the marina? |
2015-04-15 |
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Carla pose la question : In a marina, 3/4 of the boats are white, of the remainder 4/7 are blue, the rest are red. There are 9 red boats. How many boats total are in the marina? My answer is 84 because if 1/4 of the boats are divided into sevenths, that makes the whole marina a 28 part item. 3/28 are red so 84 is the total number of boats. My child thinks I am wrong. Penny Nom lui répond. |
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Mary gave her sister 5/8 of her nuts |
2015-01-22 |
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Valence pose la question : Mary gave her sister 5/8 of her nuts. Her sister gave her friend 2/3 of the amount, and her cousin 1/3 of the remainder. If Mary's sister had 50 nuts left, how many nuts had Mary. Penny Nom lui répond. |
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Filling a tub |
2015-01-02 |
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Mr pose la question : The cold tap can fill a bath in 5minutes,the hot tap in 15,and the waste pipe empty the full bath in 10 minutes. All three are fully open for 2 minutes,after which the waste-pipe is closed. How much longer will it take to fill the bath? Penny Nom lui répond. |
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Grandpa had an apple tree |
2014-09-14 |
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Emma pose la question : Grandpa had an apple tree. On the first day half of the apples plus one fell to the ground. On the second day, half of the remaining apples plus one fell to the ground. On the third day, half of what was left plus one fell to the ground. The tree was left with only one apple now. How many apples did the tree produce originally? Penny Nom lui répond. |
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Brandon went shopping - working backwards |
2014-07-11 |
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Sindy pose la question : Brandon went shopping & spent 1/4 of his money on shoes & 1/5 of the remainder on a new wallet. He then spent $60 on a pair of jeans. If he had $60 left, how much did Brandon start with? Penny Nom lui répond. |
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Working backwards |
2013-07-28 |
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Petal pose la question : Tom bought some oranges. He threw 37 rotten oranges and bought 56 more. Finally he had 220 oranges. How many oranges did Tom had at first? Penny Nom lui répond. |
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How many oranges? |
2012-10-06 |
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Rodger pose la question :
Question from Rodger, a teacher:
How Many Oranges?
Marjorie, Colleen, and Bob picked oranges together. They were tired after picking a large number of oranges and so fell asleep. Marjorie woke first and decided to take her third of the oranges and head home. She counted the oranges, and found that the number was divisible by 3 if she took one of the oranges first. Marjorie took one orange and then took one-third of the remaining oranges. She left quietly.
Bob awoke a short time later, noticed that Colleen was sleeping, and presumed Marjorie had gone for a walk. He decided to head home because he wasn't feeling well. Not realizing that anyone had left, he counted the oranges and found that the number of oranges was two more than a number that could be easily divided by 3. So he took the two extra oranges and then one-third of what was left. He left without waking Colleen and without waiting for Marjorie to return.
Colleen finally awoke and wondered where her friends had gone. She assumed they were both busy somewhere nearby. Before she left, she counted the oranges and was surprised at how small the number was. She found that the number of oranges was one more than a multiple of three, so she took the extra orange and one third of those remaining.
1. What was the total number of oranges the friends picked?
2. How many oranges were left behind when Colleen departed?
3. Is more than one answer possible for the total number of oranges? If so, what other numbers are possible? Explain.
4. Based on the values you found in problem 3, determine a reasonable solution to the problem. Explain your answer.
5. Is it possible that five oranges remained after Colleen took her share? Explain.
6. Could there have been six oranges left after Colleen departed? What about 46 oranges initially? Explain
7. Find a pattern that gives all the possible numbers of oranges that the friends picked. Explain your pattern
5. Is it possible that five oranges remained after Colleen took her “share”? Explain.
6. Could there have been six oranges left after Colleen departed? What about 46 oranges initially? Explain
7. Find a pattern that gives all the possible numbers of oranges that the friends picked. Explain your pattern Penny Nom lui répond. |
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Working together |
2011-12-30 |
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Kenneth pose la question : 15 workers can finish a job in 7 days.
If I want to find the number of days 21 workers can finish the job, the calculation becomes 1/(21 workers) X 15 workers X 7 days.
If the 21 and 15 are reduced to 7 and 5, by dividing 21 and 15 by 3, the calculation becomes 1/7 X 5 X 7 days, what do these two reduced terms (7 and 5) indicate or represent?
Do they represent 5 workers and 7 workers, as in (1/7 worker) X 5 workers X 7 days = 5 days?
I thank you for your reply. Penny Nom lui répond. |
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Problem solving |
2011-10-27 |
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keelan pose la question : a number is divided by 5. then 3 is added to the quotient. after subtracting 10, the results is 30.what is the number.t Penny Nom lui répond. |
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How much work is done? |
2011-10-15 |
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Jean pose la question : "A conical buoy that weighs B pounds floats upright in water with its
vertex "a" feet below the surface. A crane on a dock lifts the buoy
until its vertex just clears the surface. How much work is done ?" Penny Nom lui répond. |
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Working backwards |
2011-03-10 |
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Kevin pose la question : Duwayne wrote a two -digit number.He multiplied it by 3,added 18, and divided by 8.His final answer was 9.What number did Duwayne write Penny Nom lui répond. |
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Working backwards |
2010-06-22 |
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Martha pose la question : Karen spent all but $8.00 of her savings in three stores. In each store
she spent $2.00 less than half of what she had when she went in. How
much money did Karen have at the start. Robert Dawson lui répond. |
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Math in the workplace: nursing |
2010-05-24 |
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Taylor pose la question : How is math used in the workplace - Nurse Anesthetist? Penny Nom lui répond. |
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Working together |
2010-05-04 |
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Felicia pose la question : Sarah takes 3 hours longer to paint a floor than it takes Kate. when they work together it takes 2 hours. How long would each take to do the job alone? Penny Nom lui répond. |
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Working backwards |
2010-04-11 |
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adel pose la question : alice gave reggie and freddie as much money as each had already.reggie in turn gave alice and friddie as much money as each already had in negotiable treasury notes. freddie gave alice and reggie as much money as they each had. in the end they each had the same sum, 24000.00.how much money did they each in the beginning? Penny Nom lui répond. |
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A networking event |
2010-01-07 |
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Tricia pose la question : I have 70 people to go around to 10 tables with 7 at each table. only 6 from each table will rotate each time. There is 1 table monitor that always stays at same table. How do I make the rotation so everyone moves and gets to see all 70 people at the networking event? Robert Dawson lui répond. |
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Show your work |
2009-09-02 |
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Gerald pose la question : We have a 6th grade student who can solve math problem successfully without showing her work. The teacher thinks it is not fair that she doesn't show her work and the other have to and do. What sort of classroom accommodation(s) would you recommend for this type of student. It would seem to be a popular problem since there are many student who think more global than sequential. Victoria West, Penny Nom and Robert Dawson lui répond. |
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An afternoon at the races |
2009-05-15 |
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garths pose la question : A professional gambler was betting at a horse racing afternoon.
At the end of the first race he had doubled his money.
He bet R30 on the second race and tripled the money he came with.
He bet 54 on the third race and quadrupled (4 times) the money he came with.
He bet R72 on the fourth race and lost it all. But he still had R48 left.
How much money did he take to the race track? Harley Weston lui répond. |
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Mixing drinks |
2009-05-02 |
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samantha pose la question : If Steven can mix 20 drinks in 5 minutes, Sue can mix 20 drinks in 10 minutes and Jack can mix 20 drinks in 15 minutes. How much time will it take all 3of them working together to mix the 20 drinks? Stephen La Rocque and Claude Tardif lui répond. |
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Marcia's summer earnings |
2009-03-11 |
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Yasmine pose la question : Marcia saved money by working over the summer. Before school started, she spent 25%of the money of jewelry
and then 2/3 of the remaining money on a digital camera. She still had $213 left. How much money did she have
before she started shopping? Robert Dawson and Penny Nom lui répond. |
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Working together |
2009-03-04 |
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bob pose la question : T=(AB)/(A+B) using this formula t= time a,b repersenting each indivual person
i mow my lawn and it takes me 30 minutes my friend joe it takes 3 times as long,how long would it takes us together using this formula Harley Weston lui répond. |
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Three people working in pairs |
2009-02-21 |
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bevaz pose la question : A and B can together do a piece of work in 6 days, B and C together in 20 days and C and A in 7.5 days. how long will they require separately for the work? Penny Nom lui répond. |
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Ambitious 7th Grader |
2009-01-28 |
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John pose la question : I have been asked to tutor a 7th grader who is very good in math. He is taking the most advanced course that his school offers to 7th graders. This course will cover Algebra 1 over a period of two years, using McDougal Littell's Algebra, Structure and Method, Book 1, a book I like a lot.
I have been hired not to help him with his schoolwork, which is too easy for him, but to guide him through something in math beyond his schoolwork. This was his idea, an idea which surprised his parents, but one which they support.
Do you have a suggestion for me? If so, I would be very grateful to hear from you. I think this could be a lot of fun for me and my new student, if I pick the right path.
Thanks and best regards,
John
John Robert Dawson, Victoria West and Walter Whiteley lui répond. |
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A bag of coins |
2009-01-09 |
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marina pose la question : I have a bag of gold coins. I give 1/8 to mother then gave 1/2 of what was left to my brother
i give 2/7 of what was left to father. If i have 25 coins left. how many do i have originally. Robert Dawson and Penny Nom lui répond. |
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A game for 5 players |
2008-11-16 |
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safdar pose la question : five players agreed that after every game, the loser doubles every body's money. they played 5 games and everybody lost once. after the 5 games, everybody had 4128. How much money did each of the players have before the game? show your work. Janice Cotcher and Harley Weston lui répond. |
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Filling a tank with 2 taps |
2008-11-10 |
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Murray pose la question : 2 taps turned on together can fill a tank in 15 minutes. By themselves, one
takes 16 minutes longer than the other to fill the tank.Find the time taken to
fill the tank by each tap on it's own. Penny Nom and Victoria West lui répond. |
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Working together but one person starts first |
2008-09-30 |
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David pose la question : Della can scrape the barnacles from a 70 ft. yacht in 10 hours using an electric barnacle scraper. Don can do the same job in 15 hours using a manual scraper. If Della started helping Don three hours after Don started scraping, how long will it take to scrape the entire boat? Penny Nom lui répond. |
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Working together |
2008-09-22 |
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Wade pose la question : My daughter and I are having problems with this question:
Maggie can mow the lawn in 6 hrs. If her sister, Julie, helps her, it only take 2 hrs. How long
does it take Julie to mow the lawn alone. Penny Nom lui répond. |
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Filling a cistern with two pipes |
2008-05-14 |
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ramya pose la question : two pipes P and Q would fil a cistern in 30 mins and 40 mins respectively.
both pipes being opened. find when the first pipe be turned off so that the cistern may be just filled in 20 mins.
options:
1. after 10 mins
2. after 15 mins
3. after 20 mins
4. after 25 mins Stephen La Rocque lui répond. |
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Working together |
2008-05-12 |
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frustrated pose la question : Working alone, Colleen can paint a house in 2 hours less than James. working together, they can paint the house in 10 hours. How long would it take James to paint the house by himself?
Collen: 1/x-2 times 10
James: 1/x times 10
10/x-2 + 10/x = 1
10x + 10x -20 = x(x-2)
0= x^2 -22x + 20 They have the answer as 21 hours. From my previous work as you see, how are they getting 21 hours? Penny Nom lui répond. |
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Working together |
2008-04-26 |
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Joanna pose la question : If 8 men took 15 days to paint a building . How many more men are needed to paint the building in 6 days ? Stephen La Rocque lui répond. |
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It takes Mark 3 hours to paint a picture |
2008-02-27 |
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Suzanne pose la question : If Mark takes 3 hours to paint a picture and it takes Henry three times as
long to paint the same picture, then:
How many pictures can each paint in 10 hours?
How many pictures can they paint together in 10hours? Penny Nom lui répond. |
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9 employees require 15 days to complete a task |
2008-02-24 |
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Alyssa pose la question : if 9 employees require 15 days to complete a task, how long would it take to do the same work if there were 3 additional employees? Penny Nom lui répond. |
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Fibonacci numbers |
2008-01-30 |
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Beth pose la question : You've answered a question for a Linda Bach on Oct. 25, 1999 that has to do with a pet rabbit and stairs. (Working Backwards) We were wandering if there is a formula we can use to plug the numbers in? My 7th grader got that exact same problem. I've spent several hrs trying to come up with a formula. I've tried the combinations formula, the Pascal's triangle and the Permutations formula. It seems like it is something real close to those, but can't quite get anything to work. What kind of formula would work for finding the outcome of this problem? Thanks so much for your help. Beth Penny Nom lui répond. |
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Three workers working together |
2007-12-18 |
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Rajesh pose la question : Worker A can do a piece of work in 15 days, worker B in 12 days, and worker C in 10 days. Worker A works 2 days, worker B 3 days, and worker C 3 days. In what time can worker A and worker B finish the job by working together? Penny Nom lui répond. |
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How long was she be raking leaves? |
2007-10-05 |
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Skylar pose la question : A family is raking leaves. Betsy fills 3 bags to every 2 bags the Meri fill. After a while, Jim joins them. He fills 3 bags to every 2 bags that Betsy fills, but he only works half as long. When finished, they have completely filled 58 bags. If Meri takes 6 minutes to fill one bag, how long was she raking leaves? Chris Langdon lui répond. |
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How do you calculate work when force is negative? |
2007-10-02 |
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Snigdha pose la question : how do you calculate work when force is negative? Stephen La Rocque lui répond. |
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Peter and Charles mow a lawn |
2007-09-27 |
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Nancy pose la question : Peter takes 15 minutes longer to mow the lawn by himself than Charles does. Together they can mow the lawn in 18 minutes. How long would it take Charles to mow the lawn by himself? Stephen La Rocque lui répond. |
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12 men can complete a work in 8 days |
2007-09-23 |
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farah pose la question : 12 men can complete a work in 8 days. 3 days after they started working, 3 more men joined. In how many days will all of them together complete the remaining work. Stephen La Rocque lui répond. |
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Working together |
2007-09-21 |
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farah pose la question : A can do a piece of work in 10 days while B can do the same work in 15 days . They work together for 5 days and the rest of the work is done by C in 2 days . If they get 400$ for the whole work , what should be A's share. Harley Weston lui répond. |
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Ten workers perform one job in five days |
2007-08-21 |
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Kenneth pose la question : If ten workers perform one job in 5 days, one person performs one job in how many days?
Here is the calculation that I used:
(10 workers X 1 job X 5 days)/(1 person X 1 job X ? days)
The above equals 50/1, and the answer is 50 days because 50/1 = 50. In this calculation I can determine any number of workers or days if the number of jobs remains the same as that in the group of factors from the numerator (10 workers X 1 job X 5 days), that is 1 job. Here is another example to help clarify: (10 workers X 1 job X 5 days)/(? workers X 1 job X 10 days) This equals 50/10. The answer is 5 workers. So, if 10 workers can perform 1 job in 5 days, 5 workers can perform 1 job in 10 days.
Now, if I replace "1 job" from (10 workers X 1 job X 5 days) with a different number, for example, 4 jobs, this amount will prevent the calculation from producing the correct answer.
Here is an example: (10 workers X 1 job X 5 days)/(10 workers X 4 jobs X ? days) Mathematically, the calculation works, but the answer, 1.25 days, is not correct, if I'm not mistaken. If 10 workers can perform 1 job in 5 days, they cannot, by working at the same rate, perform 4 jobs in 1.25 days.
Can you explain, with a simple explanation, why the number representing the jobs in this calculation needs to be the same in the group of factors in both the numerator and in the denominator in order to provide the correct answer? Harley Weston lui répond. |
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Rate of change of distance between the clock hands |
2007-06-05 |
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Jonathan pose la question : A certain Clock has a minute hand with a length of 4 inches long and an hour hand with a length of 3 inches long. How fast is the distance between tips of these hands changing at 9:00? Stephen La Rocque lui répond. |
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An average homework grade |
2007-04-26 |
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vince pose la question : If your homework grades is only 15% of the total grades and with an average
homework grade of 90% what is your earn point for the homework
earn point = average times percent Stephen La Rocque lui répond. |
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Ridingcap's daughter |
2006-10-23 |
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Marcus pose la question : Ridingcap's daughter,whose real name was Coleen, set out for grandma's house again. This time she was delivering jam and jellies. First she stopped to see Mrs. Parsley,who took in grandma's mail while grandma was @ the hospital recovering from the wolf. Colleen gave Mrs. Parsley one third of the jars in her basket. Then Colleen set out again,and suddenly the wolf jumped out behind the bush and grubbed one half of the jars in Colleen's basket. When the wolf ran off, Colleen went on and gave Mr .Woodsman two thirds of what was left in her basket. Colleen had six jars of jam and jellies left for grandma. HOW MANY JARS DID COLLEEN LEAVE HOME WITH Stephen La Rocque lui répond. |
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How many total worker are in the factory? |
2006-08-26 |
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Sherine pose la question : One quarter of the workers at the factory are clerical, one fifth are technical, half are are administrative,and the remaining 25 are managerial.
How many total worker are in the factory? Penny Nom lui répond. |
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If all of them work together, ... |
2006-07-27 |
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Kakron pose la question : Pipe A can fill in 20 mins and pipe B can fill in 30 mins and pipe C can empty the same in 40 mins. If all of them work together, find the time taken to fill the tank? Stephen La Rocque lui répond. |
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Painting a house |
2006-06-28 |
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A student pose la question : If Sally can paint a house in 4 hours, and John can paint the same house in 6 hour, how long will it take for both of them to paint the house together? Stephen La Rocque and Penny Nom lui répond. |
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A bicycle ride around the local lakes |
2006-05-11 |
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Geecee pose la question : Yesterday I went for a long bicycle ride around the local lakes. As the ride was quite long, I rode in various stages. In the first stage I rode half of the overall distance. Stage two saw half of the remaining distance plus 35 metres covered. Stage three covered three-quarters of the remaining distance. Stage four completed half of the remaining distance plus 75 metres. Stage five completed the journey with a final burst of 150 metres.
How far did I cycle in total? Stephen La Rocque lui répond. |
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Worker A can do a piece of work in 15 days,... |
2006-03-23 |
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Kenneth pose la question : Worker A can do a piece of work in 15 days, worker B in 12 days, and worker C in 10 days. Worker A works 2 days, worker B 3 days, and worker C 3 days. In what time can worker A and worker B finish the job by working together? Penny Nom lui répond. |
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One worker can perform a certain job in 8 days |
2006-02-28 |
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Kenneth pose la question : One worker can perform a certain job in 8 days, another worker in 10 days and a third worker in 12 days. In what time can all three perform it working together? Stephen La Rocque lui répond. |
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How many passengers boarded the plane in Phoenix? |
2005-11-03 |
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Vish pose la question : Passengers boarded a plane in Phoenix. In Dallas 1/2 of the passengers got off and 4/5 of the original number got on. In Memphis 3/4 of the passengers got off and twice the number of remaining passengers got on. In Chicago 2/3 of the passengers got off the plane leaving 39 passengers. How many passengers originally boarded the plane in Phoenix? Penny Nom lui répond. |
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What number am I? |
2005-10-27 |
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Samantha pose la question : First 8 is added to me, then I am multiplied by 6. Then 40 is subtracted from me. Finally, I am divided by 10. The result is 11. What number am I? Penny Nom lui répond. |
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Snow in the driveway |
2004-04-09 |
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Patricia pose la question : Following a severe snowstorm, Ken and Bettina Reeves must clear their driveway and sidewalk. Ken can clear the snow by himself in 4 hours, and Bettina can clear the snow by herself in 6 hours. After Bettina has been working for 3 hours, Ken is able to join her. How much longer will it take them working together to remove the rest of the snow? Penny Nom lui répond. |
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Red riding hood |
2004-02-14 |
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Frank pose la question : Red riding hood had a number of jars to take to grandma's house. As she traveled she gave away 1/3 of them to an old lady. Then later As she walked through the forest a wolf stole 1/2 of her remaining jars. When she arrived at grandma's house she gave her 2/3 of the remaining jars. She kept 6 jars for herself. How many jars did she start out with. Diane Hanson lui répond. |
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Working backwards |
2003-03-14 |
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Melody pose la question : Triva went to the ardcade at the state fair to win some goldfish. She already had some goldfish at home, but wanted more. She won enough goldfish to double her stock. Her mom made her give four away. She put her new ones in the tank with the others, by the morning half of the goldfish had died. Triva's friend gave her six more. The next morning two-thirds of her goldfish died. She was left with two goldfish after giving one to a friend. How many goldfish did she start with? Penny Nom lui répond. |
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Dorothy and the wizard |
2003-01-24 |
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Ken pose la question :
dorothy was going to see the wizard of oz...she stopped at the bakery and bought a box of cookies. she met the scarecrow and gave him half the cookies. she ate half of the remaining cookies and threw one half cookie away. she met the tin man and gave him half the cookies. she ate half the remaining cookies and threw one half cookie away. she met the lion. she gave him half of her cookies. she ate half the remaining cookies and threw the LAST half cookie away. how many cookies did dorothy leave the bakery with? Penny Nom lui répond. |
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Filling A swimming pool |
2002-11-21 |
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Sarah pose la question : A swimming pool is being filled by three pumps. Alone pump A would take 6 hours, pump B would take 3 hours, and pump C would take 3 hours. If all three pumps are used to fill the pool, what fraction of the process is pump A. Penny Nom lui répond. |
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Painting a car |
2002-09-24 |
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A student pose la question : Dan can paint a car in 4 hours. Luke can pain the same car in 6 hours. Working together, how long would it take them to pain the same car? Penny Nom lui répond. |
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Mr. Byrd's drive to work |
2002-03-22 |
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Mr. Bollen pose la question : Mr. Byrd leaves his house at 7:00am to go to work. If he drives 40 mph he will arrive 3 minutes late and if he drives 60mph he arrives 3 minutes early. At what speed will Mr. Byrd have to drive in order arrive exactly on time. Please describe how you arrived at your answer. Claude Tardif and Penny Nom lui répond. |
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Making toys |
2001-12-17 |
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Karen pose la question : Jonathan and Morgan are two of Santa's elves. Jonathan can make a toy in eleven hours. Morgan can make the same toy in nine hours. How long it take for both Jonathan and Morgan to make the toy if they were working together? Claude Tardif lui répond. |
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Joan and Jan work together |
2001-09-26 |
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Karyna pose la question : Joan and Jan work together and they set up a bandstand in just 24 minutes, but if Joan does it by herself she takes 1 hour. How long would it take Jan to set up the bandstand by himself? Claude Tardif lui répond. |
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Typing a project |
2001-05-01 |
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Tom pose la question : Two students have to type a project. One can do it in 2 hours. It would take the other student three hours. They have 2 type writers. How fast can they finish by working simultaneously? Claude Tardif lui répond. |
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Working together |
2001-04-26 |
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Stephanie pose la question : Tom takes 10 hours to piant a mural on the wall of Evergreen School. Carol takes 6 hours to do the same job. If they work together, how long will it take them to paint the mural? Claude Tardif and Penny Nom lui répond. |
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Tonya in the orange grove |
2001-04-25 |
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A parent pose la question : Tonya was helping in the orange grove. She decided to take some oranges home to share with 3 friends. She gave 3 more than half to Jennifer. Angela got half the remainder and 3 more. She gave Josie half the remainder plus three. When she got home, she had only 10 oranges left. How many did she have when she left the grove? Penny Nom lui répond. |
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A bargin with the devil |
2001-03-21 |
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DJ pose la question : There once was a boy who spent all his time dreaming about getting rich. " I would do anything to be rich". The devil, hearing this, appeared before the boy and offered to make him rich. "See that bridge?" said the devil. Just walk across and I will double your money you have now. In fact, each time you cross I will double your money. There is just one thing you must give me $24 after each crossing. The boy agreed. He crossed the bridge, stopped to count his money and, and sure enough, it had doubled. He paid the devil $24 and crossed again. Again his money doubled. He paid another $24 and crossed a third time. Again his money had doubled, but this time there was only $24 left which he had to pay the devil so he was left with nothing. The devil laughed and vanished. - How much money did the boy start with?
Penny Nom lui répond. |
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A merchant from Pisa |
2001-02-11 |
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A student pose la question : A merchand doing business is Lucca doubled his money there and spent 12 denarii. On leaving, he went to Florence, where he also doubled his mone and spent 12 denarii. Returning home to Pisa, he there doubled his money and again spent 12 denarii, nothing remaining. How much did he have in the beginning? Claude Tardif lui répond. |
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Motivators |
2001-01-16 |
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Michelle Stapley pose la question : Do you know of any (or where I can find) student motivators for math at the secondary level? Basically any way I can motivate my students to WANT to learn math. Penny Nom lui répond. |
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Networks of satellites and linear spaces |
2000-12-08 |
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David pose la question : Let us suppose some companies have collaborated to place several satellites in orbit. Let us call the set of all satellites that a given company helped place in orbit a network. Finally let us assume the following 4 rules. - There are at least two distinct satellites.
- For each pair of satellites there is exactly one network containing them.
- Each network contains at least two distinct satellites.
- For each network, there is a satellite not in it.
What is the least number of satellites. what is the least number of networks? Penny Nom lui répond. |
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Job outlook |
2000-04-12 |
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Shelby Faust pose la question : what is the future demand, in numbers, of a secondary mathematics teacher? what are the projected costs for this career? what technology skills will be needed for this career? Walter Whiteley lui répond. |
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Careers after a math degree |
2000-03-31 |
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Jeanne Hyer pose la question : What type of careers can a person have with a math degree, and what is the closest thing that you have to an undergraduate degree in financial mathematics? (Administration, math, actuarial science, etc.) Harley Weston lui répond. |
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Working Backwards |
1999-10-16 |
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Linda pose la question : I am having problems finding examples of problems that require "Working Backwards" used as a strategy for solving. We are required to give a presentation on Monday, October 25, 1999 in our school districts math class. We are trying to become better problem solvers and how to teach problem solving in the elementary classroom. Help! I can't find anything in my web searches. Penny Nom lui répond. |
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Work jobs |
1999-04-19 |
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Cindy Miller pose la question : Hi. I'm a college student, majoring in Elementary Education. This semester I am taking a math class for elementary school teachers. I'm not sure if you can help out, but here is what I need. For the class, I am supposed to make 10 work jobs for students. Simple things that teach math that students can work on individually, for example after finishing a test. If you have any suggestions, I would really appreciate it. Penny Nom lui répond. |
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A Car Wash |
1998-04-04 |
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Lisa Gotimer-Strolla pose la question : Al washes a car in six hours. Fred washes a car in eight hours. How long will it take them to wash a car together? Harley Weston lui répond. |
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