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Strings of 4 digits from 1,2,...,7 |
2004-12-09 |
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Tom pose la question :
How many different combinations can be made of the numbers 1-7 in 4 string combinations in any order? EX:7-2-3-5, 3-5-1-7, etc...
And if you were to include the same 2 numbers in every combination, how many would that make? EX: Using 1 & 2: 1-2-7-4, 5-1-4-2, 2-7-5-1, etc...
Penny Nom lui répond. |
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Combinations |
2004-12-09 |
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Keith pose la question :
i have a bucket that can hold 12(or x) number of rocks. if i have 13(or y) rocks how many different combinations of rocks can i put in the bucket without having the exact same 12(or x) rocks in the bucket. is there a formula that can be used for this problem in all cases and if so how and why does it work.
Penny Nom lui répond. |
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A regular hexagon is inscribed in a circle. |
2004-12-08 |
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Abraham pose la question :
A regular hexagon is inscribed in a circle. What is the ratio of the length of a side of the hexagon to the minor arc that it intercepts?
(1) pi/6
(2) 3/6
(3) 3/pi (This is the correct answer.)
(4) 6/pi
I found the length of the minor arc to be (pi)(r)/3 by doing a sixth of the circumference(2pi r).But I can't find the length of the radius to finish off the problem. If I knew the radius I would then plug it into the above and then use the radius again to be the length of the side because the triangle(one of the six of a hexagon) is equilateral. But can you show me how to get the radius to be 3? Thank you so much.
Walter Whiteley lui répond. |
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A belt around two pulleys |
2004-12-07 |
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Ian pose la question :
a belt is stretched around two pulleys whose centers are d units apart and whose radii are R and r respectively (obviously R+r<d). the challenge is to find the length of the belt, l as a formula in terms of R, r, and d only.
Penny Nom lui répond. |
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An arc of a circle |
2004-12-05 |
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Ruben pose la question :
i have an arc 55 inches wide, 12 inches high at the centerline of the arc. how can i determine the diameter of the circle that would correspond to the arc.
Penny Nom lui répond. |
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Geometric sequence |
2004-12-04 |
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Lesa pose la question :
Find a formula for the geometric sequence: (√3 - √2), (4 - √6), (6√3 - 2√2), …
Penny Nom lui répond. |
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Probability |
2004-12-04 |
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A parent pose la question :
Consider a 30 sided polygon. If three diagonal are selected at random, what is the PROBABILITY that they share a common endpoint?
Denis Hanson lui répond. |
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J'ai deux fois l'âge que tu avais quand |
2004-12-03 |
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Un eleve pose la question :
Julien dit à Nicolas:"J'ai deux fois l'âge que tu avais quand j'avais l'âge que tu as.Quand tu auras l'âge que j'ai la somme sera égale à 63".A toi de trouver l'âge de Julien et de Nicolas.
Claude Tardif lui répond. |
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"a" cubed minus "b" cubed |
2004-12-02 |
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Denise pose la question :
"a"cubed minus "b"cubed equal (a-b) times
("a"squared plus "ab" plus "b"squared)?
I know this is a formula, but why is it true?
Penny lui répond. |
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Select a card from the deck. |
2004-12-02 |
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Heidi pose la question :
Select a card from the deck. What is the probability that this card will be red? Show the number of expected outcomes versus the number of total possible outcomes. What type of event does this represent?
Penny lui répond. |
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1/x + 1/y = 2/31 |
2004-12-01 |
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matt pose la question :
I have this problem which I think is a bit more tricky than usual.
x and y are positive integers.
1/x + 1/y = 2/31
Claude Tardif lui répond. |
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e = ln(b/a) solve for a |
2004-12-01 |
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Daniel pose la question :
I am trying to make "a" the subject of this equation "e = ln(b/a)" but am not sure if i'm doing it right. Any help would be appriciated,
Claude Tardif lui répond. |
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The volume of a sphere |
2004-11-30 |
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Lyndsay pose la question :
twenty cubic metres of air are pumped into a spherical hot air balloon with each given diameter: 1.0m; 2.0m; 3.0m; 4.0m; 5.0m;6.0m
a)calculate the new diameter, new suface area, and new volume of each balloon.
Penny Nom lui répond. |
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The substitution method |
2004-11-28 |
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A student pose la question :
I Was working and i ran into this problem can you help me solve it using the substitution method?
-3x-2y=-10
x+5y=-27
Penny Nom lui répond. |
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The tangent line at an inflection point |
2004-11-28 |
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Louise pose la question :
the equation of the tangent line to the curve y = x3 - 6x2 at its point of inflection is...
Penny Nom lui répond. |
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