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Increasing the weight |
2000-03-23 |
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Lee Millard pose la question : A weight of dimension a, b is to have its weight increased by w% by bolting plates of the same material along the top and one side (but not at both ends). The top plate and side plate have the thickness, x. Find the thickness of the plates for a given weight increase of w%. Penny Nom lui répond. |
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Sylvester's Problem |
2000-03-23 |
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Sheryl Webb pose la question : I am trying to find a proof of the theorem: Given n points in a plane, there is a line that contains exactly two points. Chris Fisher lui répond. |
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A parabola problem |
2000-03-23 |
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Morin pose la question : I need to prove that if parabola x2=4py has a chord (not necessarily a focal chord) intersecting it at points A and B, with tangents to the parabola at points A and B that intersect at C, then a line drawn through C and the midpoint of the chord M is parallel to the y-axis. Further, prove that the point D where this line intersects the parabola is the midpoint of line CM. Penny Nom lui répond. |
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Reflex angles |
2000-03-22 |
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D. Reed pose la question : What is the name of an angle that exceeds 180 degrees? Penny Nom lui répond. |
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Rule of 78 |
2000-03-22 |
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Dan Baumgarten pose la question : Can you explain the rule of 78 and the reverse rule of 78? Thanks. Claude Tardif lui répond. |
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Surface area of a sphere |
2000-03-22 |
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Gina Wilkie pose la question : How can I demonstrate to my middle school students the reason for the formula for the surface area of a sphere? Walter Whiteley and Chris Fisher lui répond. |
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I am in lowest terms. |
2000-03-21 |
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Travis Fox pose la question : I am in lowest terms. When you double my numerator and my denominator the result is 10/15. Penny Nom lui répond. |
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Compounding continuously |
2000-03-21 |
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Gina pose la question : You deposit $1500 in an account that pays 6.5% annual interest, compounded continuously. Find the balance after 10 years. I'm not sure what to do with the "compounded continuously" part. Penny Nom lui répond. |
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Binomial coefficients |
2000-03-21 |
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Howard Lutz pose la question : How do you find each successive numerical term in this equation y+dy=(x+dx)5 =x5+5*x4dx+10*x3(dx)2+10*x^2(dx)3+5*x(dx)4+(dx)5 I would appreciate an explanation of the method to find the numeric coefficient in a binomial expansion Penny Nom lui répond. |
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A system of equations in five unknowns |
2000-03-20 |
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Will pose la question : I have been having some problem with the following question for some time. I would appreciate any help on solving the problem or a solution. Q: Assume that a system of equations in the unknowns x1, x2, x3, x4 and x5 when converted to row echelon form gives . . . Penny Nom lui répond. |
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root(-1)* root(-1) |
2000-03-20 |
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Michael Moran pose la question : i squared = -1 but i squared = root(-1)* root(-1) = root( -1*-1) = root(1) = 1 -1 doesn't = 1 can you help me with my question Claude Tardif lui répond. |
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Travelling from A to B |
2000-03-20 |
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Matt pose la question : A car is traveling from point A to point B. Point A and point B are 30 miles apart. A car travels 30 miles an hour from point A to point B and then goes back to point A. How fast does the car have to go back to average 60 miles an hour? Claude Tardif lui répond. |
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Six digit numbers using 1,2,5,6,7, and 9 |
2000-03-20 |
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Rachel pose la question : How many different six-digit numbers can you make using the digits 1,2,5,6,7, and 9? How many of these six digit numbers are divisible by six? Claude Tardif and Denis Hanson lui répond. |
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A quantitative methods course |
2000-03-19 |
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Mark Haberman pose la question : Question: Last semester, the grade distribution in a quantitative methods course had the following distribution: 10% A, 25% B, 35% C, 10% D, and 15% W (withdrew). - If this grade distribution does not change this semester, what is the probability that a randomly selected student will make at least a D?
- If this grade distribution does not change this semester, what is the probability that a randomly selected student will fail the course?
- If this grade distribution does not change this semester, what is the probability that a randomly selected student who finished that course (did not withdraw) made a grade of D or better?
Harley Weston lui répond. |
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The Terror Run |
2000-03-18 |
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Danny Mclean pose la question : A fairground's most popular attraction is a roller coaster ride known as the Terror Run. One stretch of track is called the Missile Path and is in the form of a parabolic curve. B is 180m horizontally from A and the highest point of the curve is 100m above A and B. A.. The owner works out a quadratic expression to describe the Missile Path. What is the expression He found? B.. A safety Engineer examined the structure and observed that points A and B were likely to be damaged due to the steepness of the Missile path near these points. The owner can see no way to make the Missile path less steep near A and B and to keep the height of the ride the same. HOW CAN IT BE DONE? Harley Weston lui répond. |
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