In a rectangular prism, if the length and width are each increased by *p*%, by what percent must the height be decreased so that the volume remains the same?

- p

In a rectangular prism, if the length and width are each increased by *p*%, by what percent must the height be decreased so that the volume remains the same?

- p

Wendy, the chemist, had a test tube containing a mixture of acid and water. She added an ounce of water, resulting in a mixture that was 20% acid. Then, she added an ounce of acid to that new mixture, and the result was 33⅓% acid. What was the percentage of acid in the original mixture?

The combined volume of two cubes of different sizes, each having edges of integer values, is equal to the combined length of all their edges. What are the dimensions of the two cubes?

If the ratio of 2*x* – *y* to *x* + *y* is 2/3, what is the ratio of *x* to *y*?

- 1/5
- 4/5
- 5
- 6/5
- 5/4

If *f*(1) = 2 and *f*(*n*) = *f*(*n* – 1) + *n*, then what’s a formula for *f*(*n*)?

A particle moves in a straight line so that its speed is constant for a mile and then changes abruptly for the next mile and is constant for that mile, then changes again, and so on. It moves so that its speed for a given mile varies inversely as the total integral number of miles previously traveled. If the second mile is traversed in 2 hours, how long does it take to travel the *n*th mile?

If you are tired of feeling broke all the time, here is some algebra that will cheer you up.

Let *m* be the amount of money that you actually have now,

and let *n* be the amount of money that you think you need.

*A*, their average, is given by

*A* = (*m* + *n*) / 2, as usual.

Now, follow this argument and see how much better you feel.

*m* + *n* = 2*A*

Multiply both sides by (*m* – *n*).

(*m* + *n*)(*m* – *n*) = 2*A*(*m* – *n*),

*m*^{2} – *n*^{2} = 2*Am* – 2*An*.

*m*^{2} – 2*Am* = *n*^{2} – 2*An*,

Now, add *A*^{2} to both sides.

*m*^{2} – 2*Am* + *A*^{2} = *n*^{2} – 2*An* + *A*^{2}.

Thus (*m* – *A*)^{2} = (*n* – *A*)^{2}.

So (*m* – *A*) = (*n* – *A*), and then *m* = *n*.

So you have all the money you need.

Isn’t mathematics wonderful? But how can this be? Can you find a flaw with this reasoning?

A certain make of ball-point pen was priced at 50¢ at Chuck’s Bargain Bin, but nobody was buying it. Chuck reduced the price by putting the pens on sale, and then all the remaining pens sold for a total of $31.93. What was the sale price of a pen?

A nasty number is a positive integer having at least four different factors such that the difference between one pair of factors equals the sum of another pair of factors. For instance,

6 is nasty because 6 – 1 = 2 + 3

24 is nasty because 12 – 2 = 4 + 6

30 is nasty because 15 – 2 = 10 + 3.

Find the other six nasty numbers that are less than 180.

The √ key on your calculator is broken. (So is the y^{½} subroutine.) How can you find √173 to 3 decimal places using your calculator and nobody else’s?