61 articles trouvés pour ce sujet.
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Arithmétique modulaire |
2008-01-10 |
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hausknecht pose la question :
ma grand mère a entre 60 et 80 ans.il y a un an son âge était un multiple de 3.dans deux ans son âge sera un multiple de 2,de 3 et de 9.cette année , c'est un multiple de 5.quel est l'âge de ma grand mère?
Claude Tardif lui répond. |
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mod n |
2005-04-26 |
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Jean pose la question :
Réecrire (5A27)en base 16 changer en base 8
( (2n)!+ 1) (mod n)
(1-764n) (mod n)
(n+1)exposant 78355 (mod n)
PPCM(n!+1 , n!)
Claude Tardif lui répond. |
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le système RSA |
2005-02-19 |
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Un eleve pose la question :
Je suis actuellement en classe préparatoire MP au lycée Henri Poincaré de Nancy et je souhaiterais obtenir des informations sur l'exponentiation modulaire car je réalise un TIPE sur la cryptographie et plus particulièrement le système RSA. pourriez-vous m'indiquez en quoi consiste l'exponentiation modulaire et comment cela fonctionne.
Claude Tardif lui répond. |
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The modulus of a complex number |
2016-07-29 |
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Cheyenne pose la question :
There's a question on my Summer Assignment I cant figure out. Here it is:
Find the absolute Value of the complex number. -5i
Please help?
Penny Nom lui répond. |
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Calendar arithmetic |
2016-02-14 |
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Jenalee pose la question :
January 1, 2001 is Julian Day 2 451 911 (the number of days that have passed since Day 0, January 1, 4713 BC).
If Julian Day 0 was a Monday, what day of the week was January 1, 2001?
Victoria West lui répond. |
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A model of the sun and the Earth |
2014-06-14 |
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Lynn pose la question :
There is a model of the sun that is 2 1/2 inches in diameter. This is the only clue we have! How far away is the earth from this model?
Penny Nom lui répond. |
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What is the value of |2((i)^(1/2))|? |
2013-07-22 |
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Delilah pose la question :
What is the value of |2((i)^(1/2))| ?
i.e. absolute value of 2 multiplied by square root of i.
Penny Nom lui répond. |
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Mod versus Rem in Turing |
2013-01-01 |
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Eric pose la question :
I am a teacher teaching computer science using Turing. I am having
difficulty understanding why one would use the mod operator versus the rem
remainder operator.
Mod seems to make the resulting sign depend on the sign of the divisor,
whereas rem makes the resulting sign depend on the dividend.
Examples:
11 mod 5 = 1 and 11 rem 5 =1
-11 mod 5 = 4 and -11 rem 5 = -1
11 mod -5 = -4 and 11 rem -5 =1
-11 mod -5 = -1 and -11 rem -5 = -1
What I can't understand is why this would matter. For example, -11 / 5 =
-2.2 and 11 / -5 = -2.2 get the same result.
So how is a remainder dependent on the sign of one of the parts?
What benefit would using one over the other have?
Any insight would be most helpful!
Eric
Harley Weston lui répond. |
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The spread of a rumor |
2012-04-09 |
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Roohi pose la question :
The function f(t) = a/(1+3e^(-bt)) has also been used to model the spread of a rumor. Suppose that a= 70 and b=3 0.2. Compute f(2), the percentage of the population that has heard the rumor after 2 hours. Compute f'(2) and describe what it represents. Compute lim t approaches infinity and describe what it represents.
Penny Nom lui répond. |
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Modular arithmetic |
2011-10-30 |
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Kim pose la question :
Hello,
I am editing a resource for students, and I think some of the answers may be incorrect.
The text I was given and my questions are in the attachment.
Any help you could give would be appreciated.
Thanks,
Kim
Harley Weston lui répond. |
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Sales as a function of advertising |
2010-12-08 |
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Adori pose la question :
The sales S(in thousands if units) of a product after x hundred dollars is spent on advertising is given by S=10(1-e^kx). Find S as a function of x if 2500 units are sold when $500 is spent on advertising.
Penny Nom lui répond. |
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(x^3 + 11x) is divisible by 6 |
2010-06-24 |
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PT pose la question :
Given that x is a non-zero integer,
how do you show that for all values of x,
(x3 + 11x) is divisible by 6?
I know it works but how do I answer the "all values of x" part?
Thanks in advance!
Robert Dawson lui répond. |
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A linear relationship |
2010-06-22 |
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Laura pose la question :
The monthly cost of driving a car depends on the number of miles driven. Lynn found that in May it cost her $300 to drive 480 miles and in June it cost her $460 to drive 800 miles.
Question: Express the monthly cost C as a function of the distance driven d, assuming that a linear relationship gives a suitable model.
Robert Dawson lui répond. |
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A scale model of a city |
2010-05-18 |
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Briana pose la question :
Well I have to create a three dimensional city for a geometry project and it requires us to use precise scal factor and well we want to build a medium sized city but our teacher said that If we make or buildings to high our houses would look like super small compared to the tall building were trying to figure out if we were to build a medium sized city what scale factor should we use to make the houses big enough to see and design?
Walter Whiteley and Tyler Wood lui répond. |
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Modelling an underpass |
2010-05-11 |
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Sue pose la question :
An engineer at the Ministry of Transport is creating the plans for a new road. This road
will cross the path of a busy railway track so it will be necessary to built an underpass for this road.
This underpass will be in the shape of a parabolic arch.
The specifications include:
-the road must be at least 10 m wide and it must have shoulders at least 2 m wide on either
side of the road.
-there must be a clearance of 3 m over all areas of the road.
What quadratic equation could you use to model this bridge.
Penny Nom lui répond. |
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A model for the population of a Canadian city |
2010-04-07 |
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jess pose la question :
Let t^2 represent t-squared. The population of a Canadian City is modelled by: f(t) = 12t^2 + 800t + 40,000, where t is the time in years. When t= 0, the year is 2007.
a) According to the model, what will the population be in 2010?
B) In what year is the population predicted to be 300,000?
Penny Nom lui répond. |
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A linear relationship |
2010-02-24 |
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Mel pose la question :
This table shows the linear relationship between an aeroplane's height (above sea level) and the outside air temperature.
| h (cm) |
120 |
340 |
480 |
600 |
1040 |
T (degrees C) |
14.28 |
12.96 |
12.12 |
11.4 |
8.76 |
Find the gradient and vertical intercept of the function. Write the formula for T.
Penny Nom lui répond. |
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A 3D cardboard cupcake |
2010-01-30 |
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Margaret pose la question :
Hi,
I'm an art student and I'm attempting to build a 3D cupcake out of cardboard.
I want it to have a circular base of 8.5 inches and sides that are 7'' tall and slope outward so the top of the base is 29'.
The top with the frosting would be a detachable lid made from a cone with a base circumfrance of 29".
My problem is how to cut the side so they will slope out, I'm pretty sure there needs to be a curve, however I don't how to calculate the degree of it.
Ideally I want the sides to be a single piece of cardboard.
I also don't know how to calculate the arc needed to make a cone who's circular base's circumfrence is 29''.
Thanks,
Margaret
Stephen La Rocque lui répond. |
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Commodity price increase |
2009-11-04 |
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bharat pose la question :
if price of a commodity increases by x% the to keep the expenditure same
the decrease in consumption should be (x/(x+100))*100, why?
Penny Nom lui répond. |
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Constructing a scale model |
2009-09-27 |
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Colleen pose la question :
What is the formula i need to use to find out how to state a reasonable scale in the question below;
Suppose you were constructing a model that must sit on a piece of cardboard that is 22cm by 28cm. STATE THE REASONABLE SCALE that you can use to build a model to represent the following items. Determine the dimensions of the model.
a) a rectangular prism with a length of 5m and a width of 2m?
Penny Nom lui répond. |
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Fitting the curve y=a*exp(b*x)+c |
2009-08-12 |
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aika pose la question :
Could one show me the complete algorithm and formula for finding the coefficients (a,b, and c) in exponential regression model
y=a*exp(b*x)+c
Robert Dawson lui répond. |
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Math in everyday life |
2009-08-03 |
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Naveen pose la question :
Dear sir,
We are advised to do a project on "Mathematical modeling to solve various problems
of our everyday life/environmental related problems...... Can u plz help us by mailng some
ideas, suggestion,reference to make my project successful.... Thanking you......
Waiting for your favourable reply......
Penny Nom lui répond. |
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The scale for a model train |
2009-03-13 |
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Shelly pose la question :
Lindy is planning to build a model of a train using a scale where 2 inches represents 25ft. If the train is 60 feet long, what is the length in inches that Lindy should build the model of the train?
Stephen La Rocque and Penny Nom lui répond. |
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Two modular equations |
2008-10-08 |
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Mhiko pose la question :
please solve this Chinese remainder problem..and give me a solution or rule in order to solve this problem/
x=2mod15
x=1mod25
Stephen La Rocque lui répond. |
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Remainders |
2008-06-30 |
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vivek pose la question :
what is the remainder when 2050*2071*2095 is divided by 23 ?
this question needs to be done in as less time as possible.
Penny Nom lui répond. |
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The mean, the median and the mode |
2008-06-23 |
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Crystal pose la question :
Hi my name is Crystal,
My question is
under what circumstances will the mean, the median, and the mode all have the same value?
Stephen La Rocque and Harley Weston lui répond. |
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A linear model |
2008-05-09 |
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Shelby pose la question :
How would you write a linear model to represent the population of a city that has a population of 547,725 and a growth rate of -25,195 per year with t represents the number of years since 1994?
Penny Nom lui répond. |
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A complex number in polar form |
2007-07-23 |
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roland pose la question :
write the given complex number z in polar form lzl(p+qi) where lp + qil=1 for 3 - 4i.
Harley Weston lui répond. |
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A model for a building |
2007-07-17 |
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Carl pose la question :
A model for a building is 50 centimeters long, 38 centimeters wide, and 225 centimeters tall
on model 1 centimeter represents 2.5 meters.
I need to find the volume of the actual building in cubic meters,and the surface area of the building including
ceilings and floors. round to the nearest tenth of a square meter.
Harley Weston lui répond. |
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The "mode" of a set of numbers |
2007-06-06 |
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Anthony's mom pose la question :
we have a graph: Kindergarten has 1, 1st has 5, 2nd has 4, 3rd has 3
is the mode "1st grade" because there are more children in that grade?
Stephen La Rocque lui répond. |
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Using a stem and leaf plot |
2007-05-22 |
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Maegan pose la question :
The students in Mr.Smiths PE class collected data on the number of sit ups the students were able to do in three minutes. Use the data to create a stem and leaf plot. What is the median for the class data? range? mode?
Penny Nom lui répond. |
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Can you have median < mode < mean? |
2007-04-11 |
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Kaliela pose la question :
Can the Median > mode > mean?
Can the Mean > Mode > Median?
I don't think either of these can occur but I'm unsure why?
Penny Nom lui répond. |
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A missing observation |
2007-04-02 |
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destinee pose la question :
please help me my problem is 5,11,19,3,15,17,5,n find n given the following info.range:16 mode:5 median:8 mean:10 what the heck is the answer
Penny Nom lui répond. |
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Exponential form of complex numbers |
2007-02-12 |
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Austin pose la question :
When dealing with imaginary numbers in engineering, I am having trouble getting things into the exponential form. The equation is -1+i now I do know that re^(theta)i = r*cos(theta) + r*i*sin(theta). Just not quite understanding the order of operations. Thanks
Penny Nom lui répond. |
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A scale model |
2006-11-30 |
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Adrianna pose la question :
1) A model of a storage compartment is to a scale of 1:40. If the surface area of the model is 25 square centimeters, what is the surface area of the actual storage compartment?
a) The storage compartment in the last question has an actual volume of 8 cubic metres. What is the volume of the model?
Penny Nom lui répond. |
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A scale factor |
2006-03-25 |
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Jackie pose la question :
I need a formula or step by step help to show my child how to find missing dimensions for example: The scale factor for a model is 10 inches = ________ feet
Model 39.7 in
Actual 11.9 ft
Penny lui répond. |
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A train model is created using a scale of 1:60 |
2006-01-01 |
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Jennifer pose la question :
An "n gauge " train model is created using a scale of 1:60. If an actual train engine, the "K-4" an early twentieth-century engine,is 45 feet long, what is the length of an "N gauge" model of the engine in inches?
Penny Nom lui répond. |
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The number is increased by the sum of its digits |
2005-11-07 |
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Ernesto pose la question :
The number 1 is written on a blackboard. After each second the number on the blackboard is increased by the sum of its digits. is it possible that at some moment the number 123456 will be written on the blackboard?
Claude Tardif lui répond. |
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Three prime numbers p,q and r, all greater than 3, form an arithmetic progression: |
2005-07-18 |
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Ladis pose la question :
Three prime numbers p,q and r, all greater than 3, form an arithmetic progression: p=p, q=p+d and r= p+2d. Prove that d is divisible by 6.
Chris Fisher lui répond. |
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The sum of the digits of 2^100 |
2005-06-11 |
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Richard pose la question :
The sum of the digits was calculated for the number 2100, then the sum of the digits was calculated for the resulting number and so on, until a single digit is left.
Penny Nom lui répond. |
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Divisibility of a^2 + b^2 |
2005-05-16 |
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Ampa pose la question :
given natural numbers a and b such that a2+b2 is divisible by 21, prove that the same sum of squares is also divisible by 441.
Penny Nom lui répond. |
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Modelling monthly temperature with a cosine |
2004-12-25 |
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Regis pose la question :
The average monthly temperature for a location in Ontario as a function of month number can be modelled using the equation y = a cos[k(t + b)] + d.
Harley Weston lui répond. |
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Two modes |
2002-12-12 |
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ali pose la question :
I have a math assignment to pick the mode in a set of data. 12 and 21 both appear twice in the data set. What is the mode?
Penny Nom lui répond. |
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Mean, median and mode |
2002-09-08 |
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Ramona pose la question :
- How do you calculate the mean, median, and mode?
- what are each of their definitions?
Leeanne Boehm lui répond. |
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The Dugout, Don's Basement, Cd Corner,... |
2002-04-30 |
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A student pose la question :
The Dugout, Don's Basement, Cd Corner, Harry's Deli, Bill's Software, Anne's Footwear, and Joanne's House cleaning. The gift certificates are each in multiples of $5. There is a $100 range in the value of the gift certificates, which start at $25. The mean value of all seven gift certificates is $80, and the median and mode are both $70. The certificate from The Dugout is worth the most and the one from Joanne House cleaning is worth the least. The total value of the gift certificates from CD Corner, Harry's Deli, and Anne's Footwear is $270, but Anne's Footwear certificate is worth $50 more than the one from Harry's Deli. The Cd Corner gift certificate is equivalent to the mean for this group of three. What is the value of the gift certificates from each store?
Penny Nom lui répond. |
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Take It! |
2002-04-03 |
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Bryan pose la question :
You are playing Take It! for $180,00 with a total stranger. There are 180 identical balls in a big vase. Each player in his turn, reaches into the vase and pulls out 1,5,or8 balls. These balls are discarded. The player who takes the last ball from the vase wins the $180,000. A flip of the coin determines that you will go first. Are you glad? How many will you take out on the first move, and how will you proceed to win the prize?
Claude Tardif lui répond. |
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The best linear model |
2001-07-29 |
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Rebeca pose la question :
I am a student (senior) summer hire working for Dept of the Army Resource Management. I've been assisting the Analyst in developing a model to predict training costs. The technique we used was simple linear regression. Now I've been asked for my opinion in choosing the best model I feel is better. I've chosen #1. Garrison Training but I want a second opinion before I give my choice. I've taken basic statistics last year in high school and will probably be taking more this year. Could you look over the information and give me a reason my choice would not be best? The dep variable-y, is Training costs in dolars per day. | Model | Ind Variable- X | a | b | r | sy.x | | 1. | Garrison Training | 126.31 | 0.982 | 0.9055 | 117.2 | | 2. | Local Training | 212.16 | 1.37 | 0.7937 | 142.7 | | 3. | Man Rig Area | 116.38 | 2.47 | 0.6481 | 175.6 | | 4. | Major Training | 346.12 | 4.67 | 0.7280 | 167.2 |
Andrei Volodin lui répond. |
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Conservation, consumption and population growth |
2001-06-04 |
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Steve pose la question :
I'm trying to quantify the relation between conservation/consumption and population growth. For instance let's consider California: The 2000 census states that California's population grew from 29,760* in 4-1990 to 33,871 in 4-2000. I want to find r or rate of growth per year. Based on the exponential growth formula for population growth:
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Penny Nom lui répond. |
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Toy bricks |
2001-05-13 |
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Sarah pose la question :
A regular-sized brick weighs 4 kilograms. How much will a similar toy brick, made of the same material, but all of the same dimensions of which are four times smaller, weigh? The 300-metre tall Eiffel tower is made of steel and weighs 8 000 000 kg. An exact replica, made of the same material, weighs 1 kg. How high is the replica
Penny Nom lui répond. |
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What is the difference between Mean and Average? |
2000-12-13 |
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Julie pose la question :
What is the difference between Mean and Average? My thinking is the average, is the equal to the sum of all numbers divided by the number of numbers added together. But the mean, I think should be calculated by adding the largest and smallest numbers in the set and them dividing by 2. (which is the point where 1/2 the numbers are higher and 1/2 the numbers are lower)
Patrick Maidorn and Penny Nom lui répond. |
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Mode |
2000-09-22 |
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James Barton pose la question :
I have always been told that a mode is the "one" number that appears most in the set of numbers: ex.{1,3,4,6,3,2} the mode is 3. What if you have {1,1,3,4,5,5}is there a mode. I was taught long ago that there is no mode, Not i am having to teach there is two modes. 1 and 5. If this is the case if we have {1,1,2,2,3,3,4,4,5,5} that every number is the mode. True or false. This is being ambigiuous if we say all are the mode. Because no one number is used more than the others.
Claue Tardif and Harley Weston lui répond. |
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Finding a formula |
2000-05-05 |
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Erica Hildebrandt pose la question :
If a farmer has a field and his plots are laid out in the following grid where each # represents a plot: | 4 | 5 | 12 | 13 | 20 | | 3 | 6 | 11 | 14 | 19 | | 2 | 7 | 10 | 15 | 18 | | 1 | 8 | 9 | 16 | 17 | Of course the plot numbers aren't meaningful as I have described above. In fact they may not be numbers at all. The only constants I have are the total number of rows and columns. Using the total number of rows and columns and my current position row and column, how can I write a formula that tells me column 3 row 3 = 10, column 4 row 2 = 14, etc. I can see the pattern but can't quite get the formula. I believe I will need 2 different formulas one for even and one for odd rows.
Paul Betts and Penny Nom lui répond. |
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A model area |
1999-12-15 |
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John Ost pose la question :
Hello, I am a college student taking an elementary math course I need if possible assistance to developing an area model 36 x 25 that shows each of the four separate partial products. I must know how to do the computation 36x25 showing each of the four partial products separately, and indicate how each corresponds to the drawing that is required of the area model.
Penny Nom lui répond. |
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Mean, median and mode |
1999-12-07 |
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J William Morning pose la question :
Using the data values 2,2,10,6,5, determine the median, mode and mean.
Penny Nom lui répond. |
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Linear models |
1999-11-09 |
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Helen Moreno pose la question :
What is a linear model?
Harley Weston lui répond. |
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Mean, median and mode |
1999-11-06 |
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Rick pose la question :
I have five number places and the mean and median are both "0". The mode is greater than the mean. The sum of the absolute values of all of the numbers is 20. The smallest number is 4 less than the next smallest number. What are the five numbers. (negative integers can be used) All of the numbers are integers.
Penny Nom lui répond. |
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Divisibility by 9 |
1999-02-21 |
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Razzi pose la question :
I've been having a hard time trying to solve the following problem and I was wondering if you could help me. For any positive integer a let S(a) be the sum of its digits. Prove that a is divisible by 9 if and only if there exist a positive integer b such that S(a)=S(b)=S(a+b).
Chris Fisher and Harley Weston lui répond. |
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Modular Arithmetic |
1999-02-04 |
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Leslie Kupper pose la question :
I am trying to do a project on modular arithmetic. I was wondering if there were any websites that include a sample lesson plan on modular arithmetic for any grade level. Let me know where and how to find them. Thanks.
Harley Weston lui répond. |
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Absolute value of i |
1999-01-06 |
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Wayne Bagley pose la question :
I would like to know what is the absolute value of i. I need an answer suitable for the secondary level.
Harley Weston lui répond. |
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A Logic Problem |
1998-06-07 |
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Anthony Bacigalupo pose la question :
My name is Anthony Bacigalupo and I take Sequential ][ Math and am taking a practice regents. When doing a logic problem, I encountered the following statements, where I am trying to prove P ( I left out steps unrelated to the question)....
Chris Fisher lui répond. |
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Clock Arithmetic. |
1998-03-09 |
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Joann Dixon pose la question :
What is clock mathematics?
Patrick Maidorn lui répond. |
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