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Can the standard deviation ever = 0? |
2002-02-16 |
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Karen pose la question :
If given a class of 30 people who take a test with a mean of 80. Can the standard deviation ever = 0? If so, why?
Penny Nom lui répond. |
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Diameter of a pipe |
2002-02-16 |
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Landry pose la question :
I am trying to calculate the dia. of a pipe 60 inches long that will hold a gallon of water. What is the formula?
Penny Nom lui répond. |
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The perimeter of an ellipse |
2002-02-14 |
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Harry pose la question :
I am planning to build a coffe table with an ellipse of 24x36 for the top. I wish to decorate the edge and need to know the lenght of the perimeter for lay out purposes. Is there an easy way to approximate this figure with out using intergal calculus?
Penny Nom lui répond. |
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Nets for pyramids |
2002-02-14 |
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Michelle pose la question :
I want to have my students create nets for pyramids and I need to know how to find the correct range of degrees for the interior congruent angles of the isosceles triangular faces. For example, I know for a square-based pyramid that 77 degrees will work; however, I know other angle measures will also work. I'm just not sure how to find the minimum degree measure to have the net actually "work". I'm assuming the maximum would be 89 degrees, although that would make for a very tall pyramid.
Penny Nom lui répond. |
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36 is 20% less than _____? |
2002-02-13 |
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Lori pose la question :
36 is 20% less than _____?
Walter Whiteley lui répond. |
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A man and his wife walk up a moving escalator |
2002-02-13 |
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Monty pose la question :
A man and his wife walk up a moving escalator. The man walks twice as fast as his wife. When he arrives at the top, he has taken 28 steps. When she arrives at the top, she has taken 21 steps. How many steps are visible in the escalator at any one time.
Peeny Nom and Claude Tardif lui répond. |
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What is 20 to the thousandth power? |
2002-02-12 |
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Kristi pose la question :
What is 20 to the thousandth power?
Paul Betts lui répond. |
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Three bugs on a line |
2002-02-12 |
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Murray pose la question :
- Three bugs are crawling on the coordinate plane. They move one at a time, and each bug will only crawl in a direction parallel to the line joining the other two.
- If the bugs start out at (0,0), (3,0), and (0,3), is it possible that after some time the first bug will end up back where it started, while the other two bugs switch places?
- Can the three bugs end up at (1,2), (2,5), and (-2,3)?
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- A single peg is placed at the bottom left-hand corner of a grid that extends infinitely far up and to the right. You play a game in which you are allowed to make the following move: if the hole immediately above and the hole immediately to the right of a peg are both empty, you can remove the existing peg and place pegs in those two holes instead.
- Show that, no matter how you move, you can never remove all the pegs from the 3-by-3 square at the bottom left-hand corner of the grid. (b)
- Is it possible to remove all the pegs from the six holes closest to the bottom left-hand corner of the grid (the region indicated in the picture below)?
Claude Tardif lui répond. |
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The slopes of the sides of the Great Pyramid |
2002-02-09 |
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Christina pose la question :
The Great Pyramid is the largest of the Egyptian pryamids. When it was built, it was 481 feet tall and had a square base with 755-foot sides. The pyramid has two different slopes-one along its sides and the other along its edges. Which slope is steeper?
Penny Nom lui répond. |
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The number of hidden cubes |
2002-02-05 |
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Katie pose la question :
This problem is about finding the number of cubes visible and hidden in a cube.
In a cube that is 3x3, 19 cubes can be seen. 8 are hidden.
In a cube that is 4x4, 37 cubes can be seen. 27 are hidden.
In a cube that is 5x5, 61 cubes can be seen. 64 are hidden.
In a cube that is 6x6, 91 cubes can be seen. 125 are hidden. The question is:
Explain how you could find the number of small cubes that are visible and hidden in a cube of any size.
Paul Betts and Penny Nom lui répond. |
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Parabolas |
2002-02-03 |
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Kuang pose la question :
-Who is credited for working with or studying the Parabola? -What is a conic section? -What does a parabola look like? -How is a parabola formed? -Where and how are parabolas used today in the real world?
Harley Weston lui répond. |
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Number conversions and averages |
2002-02-03 |
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A student pose la question :
A table has the measurements of 1.6m by 2m, how much material is needed to cover table? I converted to cm then multiplied but got an answer of 32000cm ,so I divide by 100 to get to metres - the answer was 320 which I know is wrong - please explain!! Also I need to explain in my own words what an 'average' is and I am struggling.
Penny Nom lui répond. |
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Square arrangements of clovers |
2002-02-03 |
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Cassie pose la question :
Clyde had a strange fascination with numbers. One day he decided to mount his 4 leaf clover collection in groups of square numbers.he took a long piece of butcher paper and glue and began this arduous task.There was 1 clover,4 clovers.and then 9 clovers in the third set. what would be in the seventh set of 4 leaf clovers?
Penny Nom lui répond. |
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Zeta[2]=(Pi2)/6 |
2002-02-02 |
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alex pose la question :
Can you please tell me a proof that Zeta[2]=(Pi2)/6
Chris Fisher lui répond. |
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I am a fraction |
2002-02-01 |
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Anthony pose la question :
I am a fraction that is greater than 1 but less than 2. The sum of my numerator and denominator is 11. My denominator subtracted from my numerator is 1. What fraction am I?
Paul Betts lui répond. |
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