Problem Solving

Hi All,

We're told that BEFORE expansion, a zoo had 343 birds in 7 cages and AFTER the expansion was complete, there were 719 birds in 11 cages. We're asked for the approximate percent increase in the average number of birds per cage. This question is based around a couple of standard math Formulas: the Average Formula and Percent Change Formula.

Before the expansion, the average birds/cage was 343/7 = 49 birds/cage
After the expansion, the average birds/cage was 719/11 = approximately 65 birds/cage

The percent increase in birds/cage = (new - old)/(old) = (65 - 49)/49 = 16/49 = approximately 1/3 = approximately 33 1/3%

Final Answer: D

GMAT assassins aren't born, they're made,
Rich

BTGmoderatorDC wrote:Before expansion, a zoo had 343 birds in 7 cages. If, after the expansion was complete, there were 719 birds in 11 cages, what was the approximate percent increase in the average number of birds per cage?

a. 11%

b. 15%

c. 24%

d. 33%

e. 50%

OA D

Source: Princeton Review

The average number of birds per cage after the expansion was 719/11 ≈ 65, and before the expansion, the average number of birds per cage was 343/7 = 49.

We use the percent increase formula: (New - Old)/Old x 100. So the percent increase is:

(65 - 49)/49 x 100

Rounding 49 to 50, we have:

(65 - 50)/50 x 100

(65 - 50) x 2 = 30 percent, which is closest to 33%.

Answer: D