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The area of a right triangle |
2012-04-03 |
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From Shelli:
How do you find the area of a right triangle if you only know that the hypotenuse is 10 and that the base and height are unknown but are equal?
Answered by Penny Nom. |
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Radioactive decay |
2012-04-02 |
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From Christy:
Hello, how do I go about answering this question?
Should I be using the formula Ce^(kt)?
Given that the decay constant for Radium is -.000428/year, how long, to the nearest year, does it take a sample to decay to 15% of its present mass?
Answered by Penny Nom. |
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A question about a pattern |
2012-04-02 |
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From Steven:
| A |
B |
C |
D |
E |
F |
(G) |
| 1 |
3 |
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100 |
100 |
33 |
(67) |
D is divided by A and B to give E and F the difference between E and F is G
C is added to D to give the new D number.
| 3 |
5 |
120 |
330 |
110 |
66 |
(44) |
| 4 |
6 |
130 |
460 |
115 |
77 |
(38) |
| 5 |
7 |
140 |
600 |
120 |
86 |
(34) |
Following the pattern you might expect a massive increase in C to result in a significant decrease in G but...
| 6 |
8 |
1000 |
1600 |
267 |
200 |
(67) |
G actually increases and goes back to square 1 Why?
Answered by Robert Dawson. |
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1+2+4+8....= -1 |
2012-04-02 |
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From Andy:
In this minutephysics video, it's claimed that 1+2+4+8....= -1
Is this true, and if so, how?
< href="http://www.youtube.com/watch?v=kIq5CZlg8Rg">http://www.youtube.com/watch?v=kIq5CZlg8Rg
Answered by Robert Dawson. |
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A circle drawn around a equilateral triangle |
2012-04-01 |
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From BIMAL:
what is the diameter of a circle drawn around a equilateral triangle of size 6 cm
Answered by Penny Nom. |
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What is the better price? |
2012-03-30 |
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From john:
What is the better price?
If a bag of mulch sells for $6.75 and contains 2.7 cubit feet versus a bag selling for $5.99 and contains 2 cubit feet.
Which is the better value?
Answered by Penny Nom. |
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A lot with a slope |
2012-03-30 |
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From Carlos:
I have a lot with a slope. On the right I need to bring it up 2', From that point to the left is 112' which at this point I need to bring it up 5' for it to be level . The distance front to back is 80'. What is the cubic yards of this area that I need to fill in.
Answered by Harley Weston. |
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Golf for 17 |
2012-03-29 |
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From Richard:
Hi Guys,
I have a scheduling problem which I don't think you have covered before.
Apologies if you have!
I have 17 golfers due to play 4 rounds of golf.
Each round will consist of 3 threeballs and 2 fourballs (ie. 17 golfers in 5 groups)!
Is it possible to come up with a schedule where each golfer plays
with different partners in each round?
Answered by Robert Dawson. |
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The period T of a pendulum |
2012-03-27 |
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From Ashley:
The period T of a pendulum is given in terms of its length, l, by T=2pi sqrt(l/g) where g is the acceleration due to gravity(a constant)
a. find dT/dl
b. what is the sign of dT/dl
c. what does the sign of dT/dl tell you about the period of the pendulums?
Answered by Penny Nom. |
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A uniform probability density function |
2012-03-26 |
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From Noeline:
The label on a bottle of liquid detergent shows contents to be 12 ounces per bottle. The production operation fills the bottle uniformly according to the following probability density function:
f(x) = 8 for 11.975 ≤ x ≤12.10
and
f(x) = 0 elsewhere
a. What is the probability that a bottle will be filled with 12.02 or more ounces?
b. What is the probability that a bottle will be filled between 12 and 12.05 ounces?
c. Quality control accepts production that is within .002 ounces of number of ounces shown on the container label. What is the probability that a bottle of this liquid detergent will fail to meet the quality control standard?
Answered by Penny Nom. |
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The equation of a line |
2012-03-26 |
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From Danielle:
Hello, could you help me figure out what the equation of the line is in the form of Ax+By=C with the points (-2,0) and (0,3)?
Thank You!
Answered by Penny Nom. |
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The derivative of 2sin cubed x - 3 sin x |
2012-03-25 |
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From holly:
suppose f(x) = 2sin cubed x - 3 sin x
show that f 1(x) = -3 cos x cos 2x
Answered by Harley Weston. |
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Painting a pool |
2012-03-25 |
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From Salai:
A swimming pool measures 8m long, 6m wide and 1.5 m deep. The special paint for the pool cost $6per square metre.
How much will it cost to paint the interior surfaces of the pool ?
Answered by Penny Nom. |
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A cubic inequality |
2012-03-25 |
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From Victoria:
The flight path of a bumblebee above the ground can be modelled by the function f(x)= 2x^3- 17x^2+ 11x + 130. Where x is the time in seconds and f(x) represents the height in inches above the ground. The entrance to the bee's hive is located 100 inches above the ground. Determine when the bumblebee's height is greater than 100 inches. The bee's height was monitored from 0 to 25 seconds inclusive. (over the domain 0
Answered by Penny Nom. |
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The remainder theorem |
2012-03-25 |
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From Victoria:
When k^2 + 3kx + 13k +k^2x - 3x^2 is divided by (x-4) the remainder is 22. Find the value(s) of K.
Answered by Penny Nom. |
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