efore adding to her collection, Laura had 207 antique

BTGModeratorVI wrote: ↑

Mon Jul 13, 2020 7:49 am

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%

Answer: C
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

BTGModeratorVI wrote: ↑

Mon Jul 13, 2020 7:49 am

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%

Answer: C

Solution:

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