Before adding to her collection, Laura had 207 antique

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Vincen: Legendary Member; Posts: 2898; Joined: Thu Sep 07, 2017 2:49 pmFollowed by: 5 members; Thanked: 6 times

by Vincen » Sat Nov 30, 2019 7:32 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%

[spoiler]OA=C[/spoiler]

Source: Princeton Review

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Source: Beat The GMAT — Problem Solving | Sat Nov 30, 2019 7:32 am

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[email protected]: Elite Legendary Member; Posts: 10392; Joined: Sun Jun 23, 2013 6:38 pmFollowed by: 511 members; Location: Palo Alto, CA; Thanked: 2867 times; GMAT Score:800

by [email protected] » Sat Nov 30, 2019 10:36 am

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

Contact Rich at [email protected]

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swerve: Legendary Member; Posts: 2545; Joined: Sun Oct 29, 2017 2:04 pmFollowed by: 6 members

by swerve » Sat Nov 30, 2019 11:43 am

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

average number of figurines per box before adding to her collection $= \frac{207}{9} = 23$
average number of figurines per box before after adding to her collection $= \frac{386}{12} = 32.1$

approximate percent increase in the average number of figurines per box $= \frac{32.1 - 23}{23}\cdot 100$

$= 39.85 \approx 40\%$

Therefore, the correct answer is __C__

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Scott@TargetTestPrep: GMAT Instructor; Posts: 8156; Joined: Sat Apr 25, 2015 10:56 amFollowed by: 29 members; Location: Los Angeles, CA; Thanked: 43 times

by Scott@TargetTestPrep » Sun Dec 08, 2019 7:15 pm

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

Scott Woodbury-Stewart
Founder and CEO
[email protected]

See why Target Test Prep is rated 5 out of 5 stars on BEAT the GMAT. Read our reviews

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Brent@GMATPrepNow: GMAT Instructor; Posts: 16207; Joined: Mon Dec 08, 2008 6:26 pmFollowed by: 1268 members; Location: Vancouver, BC; Thanked: 5254 times; GMAT Score:770

by Brent@GMATPrepNow » Mon Dec 09, 2019 10:21 am

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 â‰ˆ 32 figurines per box

Percent increase = (100)(new - old)/old
â‰ˆ (100)(32 - 23)/23
â‰ˆ (100)(9)/23
â‰ˆ 900/23
â‰ˆ 39

Answer: C

Cheers,
Brent

Brent Hanneson - Creator of GMATPrepNow.com

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