 |
|
|
|
|
|
|
|
|
Strings of 4 digits from 1,2,...,7 |
2004-12-09 |
|
From Tom:
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...
Answered by Penny Nom. |
|
|
|
|
|
|
Combinations |
2004-12-09 |
|
From Keith:
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.
Answered by Penny Nom. |
|
|
|
|
|
|
A regular hexagon is inscribed in a circle. |
2004-12-08 |
|
From Abraham:
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.
Answered by Walter Whiteley. |
|
|
|
|
|
|
A belt around two pulleys |
2004-12-07 |
|
From Ian:
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.
Answered by Penny Nom. |
|
|
|
|
|
|
An arc of a circle |
2004-12-05 |
|
From Ruben:
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.
Answered by Penny Nom. |
|
|
|
|
|
|
Geometric sequence |
2004-12-04 |
|
From Lesa:
Find a formula for the geometric sequence: (√3 - √2), (4 - √6), (6√3 - 2√2), …
Answered by Penny Nom. |
|
|
|
|
|
|
Probability |
2004-12-04 |
|
From A parent:
Consider a 30 sided polygon. If three diagonal are selected at random, what is the PROBABILITY that they share a common endpoint?
Answered by Denis Hanson. |
|
|
|
|
|
|
J'ai deux fois l'âge que tu avais quand |
2004-12-03 |
|
From Un eleve:
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.
Answered by Claude Tardif. |
|
|
|
|
|
|
"a" cubed minus "b" cubed |
2004-12-02 |
|
From Denise:
"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?
Answered by Penny. |
|
|
|
|
|
|
Select a card from the deck. |
2004-12-02 |
|
From Heidi:
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?
Answered by Penny. |
|
|
|
|
|
|
1/x + 1/y = 2/31 |
2004-12-01 |
|
From matt:
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
Answered by Claude Tardif. |
|
|
|
|
|
|
e = ln(b/a) solve for a |
2004-12-01 |
|
From Daniel:
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,
Answered by Claude Tardif. |
|
|
|
|
|
|
The volume of a sphere |
2004-11-30 |
|
From Lyndsay:
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.
Answered by Penny Nom. |
|
|
|
|
|
|
The substitution method |
2004-11-28 |
|
From A student:
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
Answered by Penny Nom. |
|
|
|
|
|
|
The tangent line at an inflection point |
2004-11-28 |
|
From Louise:
the equation of the tangent line to the curve y = x3 - 6x2 at its point of inflection is...
Answered by Penny Nom. |
|
|
