###
Math Question for Saturday, October 25th, 2014

The area of a trapezoid is *h*(*b*_{1} + *b*_{2}), where *h* is the altitude, and *b*_{1} and *b*_{2} are the lengths of the parallel bases. If a trapezoid has an altitude of 5 inches, an area of 55 square inches, and one base 13 inches long, what is the length, in inches, of its other base?

**F.** 9.0

**G.** 16.8

**H.** 19.4

**J.** 45.0

**K.** 97.0

## Correct!

**The correct answer is F.**
Substituting into the formula, 55 = (5)(13 + *b*),

so 110 = 5(13 + *b*), 110 = 65 + 5*b*, 5*b* = 45, *b* = 9.

## Incorrect

If the other base were 16.8, the area would be (5)(13 + 16.8) = 74.5, not 55.

## Incorrect

If the other base were 19.4, the area would be (5)(13 + 19.4) = 81, not 55.

## Incorrect

If the other base were 45.0, the area would be (5)(13 + 45) = 145, not 55.

## Incorrect

If the other base were 97.0, the area would be (5)(13 + 97) = 275, not 55.