![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Why a Right angle? |
2000-04-03 |
![](/images/transparent.gif) |
Joseph Mizerek pose la question : I was wondering why a 90 degree angle is called a Right angle. I mean why isn't called a left angle. Haragauri Gupta lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Wholesale price |
2000-04-02 |
![](/images/transparent.gif) |
Lynda Bintz pose la question : If a product is priced at $4.99 and is marked up 40% how do I calculate the wholesale price? Penny Nom lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Running Through a Train Tunnel |
2000-04-01 |
![](/images/transparent.gif) |
Eugene Chan pose la question : A man is running through a train tunnel. When he is 2/3 of the way through, he hears a train that is approaching the tunnel from behind him at a speed of 60 mph. Whether he runs ahead or back, he will reach an end of the tunnel at the same time the train reaches that end. At what rate, in miles per hour, is he running? (Assume he runs at a constant rate.) I think the answer (12 mph) is wrong. Also, I believe it should read 1/3 of the way through, but don't know how to prove it. Could you come up with some way to prove it, please? I would really appreciate it. Penny Nom lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Filling a hole |
2000-04-01 |
![](/images/transparent.gif) |
John McNeill pose la question : I have an area 20 feet long and 12 feet wide It starts out at a depth of 4 inches and ends up at 0 inches. How much sand do I need to fill the excavation. Penny Nom lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Resolution of the equation f(x)=0 |
2000-04-01 |
![](/images/transparent.gif) |
Naoufal pose la question : How can i evalf the equation f(x)=0 with f function . Can you ansear me in french thank you very much Claude Tardif lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Symmetric Primes |
2000-04-01 |
![](/images/transparent.gif) |
Marlene Moore pose la question : Hi...Im in 9th grade and am having a hard time figuring out symmetric primes. Heres the problem: Find two pairs of symmetric primes of 20. Symmetric primes of 15? Claude Tardif lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Careers after a math degree |
2000-03-31 |
![](/images/transparent.gif) |
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. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Word problems |
2000-03-31 |
![](/images/transparent.gif) |
Amy pose la question : Question: - a north bound train left at noon. four hours later a south bound train left the same station. at 5 o'clook they were 160 miles apart. what was the rate of both if the north bound train was going 20 miles faster than the other one.
- clark's final exam was given 5 times the weight of the weight of a weekly test. the avgerage of 15 weekly test was 91. the overall weighted average was 85. what did he make on the final.
Penny Nom lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Hats, jackets and gloves |
2000-03-30 |
![](/images/transparent.gif) |
Max pose la question : Find the one that does not belong 66 333 99 111 88 also if you have 3 hats and 3 jackets and 3 gloves, how many different combinations of a hat and a jacket and gloves can you wear? Claude Tardif and Penny Nom lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Riemann sums |
2000-03-30 |
![](/images/transparent.gif) |
Joshua D. Parham pose la question : If n is a positive integer, then
lim (1/n)[1/(1+1/n) + 1/(1+(2/n) + ... + 1/(1+n/n)]
n->infinity
can be expressed as the integral from 1 to 2 of 1/x dx Penny Nom lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Making fruit salad |
2000-03-29 |
![](/images/transparent.gif) |
A grade 5 student pose la question : Miss.Muffet males a fruit salad by adding 31/2 pounds of grapes and 4 1/4 pounds of apples to every 2 1/4 pounds of melon. How many pounds of grapes does she use in 50 pounds of fruit salad? Claude Tardif lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
The world of percentage. Price tags everywhere |
2000-03-27 |
![](/images/transparent.gif) |
Lydia pose la question : I know there is a formula to be utilized for finding the percentage of a number, like most math. You just simply need to remember the formula for finding the number. Please put me on the path. How does one figure out 10% or 15% of a total number asked? Say... 120 Reverse: 15 is what percent of 120, I know the answer should be the same but how is the formula applied? Harley Weston lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Taxis in Chicago |
2000-03-27 |
![](/images/transparent.gif) |
A high school studenthigh school student pose la question : Suppose that taxis pick up and deliver passengers in Chicago, which is divided into three zones. Records kept by the drivers show that of the passengers picked up in Zone 1, 50% are taken to a destination in Zone 1, 40% to Zone 2, and 10% to Zone 3. OF the passengers picked up in Zone 2, 40% go to Zone 1, 30% to Zone 2, and 30% to Zone 3. Of the passengers picked up in Zone 3, 20% go to Zone 1, 60% to Zone 2 and 20% to Zone 3. Suppose that at the beginning of the day, 600 of the taxis are in Zone 1, 100 in Zone 2, and 300 in Zone 3. What is the distribution of taxis in the various zones after all have had two riders? Harley Weston lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Division |
2000-03-26 |
![](/images/transparent.gif) |
Kelly Allen pose la question : My 8 year old daughter had 12 bracelets which she arranged into 4 piles of 3. Did she divide 12 by 3 or by 4? Most people I've asked can only offer an opinion. What I'm looking for is a definitive answer, if there is one. My husband says the number of sets is the answer: 12 divided by 3 = 4 Most others I've asked said that the amount in each set is the answer: 12 divided by 4 = 3 Harley Weston lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
![](/images/transparent.gif) |
Divisibility by 3 |
2000-03-24 |
![](/images/transparent.gif) |
Pat Walsh pose la question : W hy does it work when you add the digits of a number then divid by three to see if the number is divisible by three Penny Nom lui répond. |
![](/images/transparent.gif) |
![](/images/transparent.gif) |