Problem Solving

Hi All,

We're told that before adding to her collection, Laura had 207 antique figurines stored in 9 boxes and that after adding to her collection, she had 386 figurines in 12 boxes. We're asked for the APPROXIMATE PERCENT INCREASE in the average number of figurines per box. This question is based on some standard math formulas (Average & Percent Change) and the word "approximate" means that we can likely round-off some of the values and still get the correct answer.

The "before" average is 207/9 = 23
The "after" average is 386/12 = 32 1/6... which we can round down to 32

Percentage Change = (New - Old)/Old = (Difference)/(Original) = approximately 9/23

9/18 = 50% and 9/27 = 33 1/3%... 9/23 is BETWEEN those values, and there's only one answer that 'fits'....

Final Answer: C

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

Vincen wrote:Before adding to her collection, Laura had 207 antique figurines stored in 9 boxes. After adding to her collection, she had 386 figurines in 12 boxes. What was the approximate percent increase in the average number of figurines per box?

A. 9%
B. 33%
C. 40%
D. 50%
E. 86%

[spoiler]OA=C[/spoiler]

Source: Princeton Review

When Laura had 207 antiques stored in 9 boxes, her average was 207/9 = 23 antiques per box. When she added more, her new average was 386/12 = 32.16, which is about 32 per box. Let's determine the percentage increase, using the formula (New - Old)/Old x 100.

(32 - 23)/23 x 100

9/23 x 100 = 39.1 percent, or about 40%.

Answer: C

Vincen wrote:Before adding to her collection, Laura had 207 antique figurines stored in 9 boxes. After adding to her collection, she had 386 figurines in 12 boxes. What was the approximate percent increase in the average number of figurines per box?

A. 9%
B. 33%
C. 40%
D. 50%
E. 86%

[spoiler]OA=C[/spoiler]

Source: Princeton Review

Please note that the word approximate typically tells us that we can use some estimation during the solution

INITIAL SITUATION
207/9 = 23 figurines per box

AFTER ADDING TO COLLECTION
386/12 ≈ 32 figurines per box

Percent increase = (100)(new - old)/old
≈ (100)(32 - 23)/23
≈ (100)(9)/23
≈ 900/23
≈ 39

Answer: C

Cheers,
Brent