BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

OG Certain toy store's revenue in November

Expert replies
by AbeNeedsAnswers » Tue Jul 25, 2017 8:11 pm
If a certain toy store's revenue in November was 2/5 of its revenue in December and its revenue in January was 1/4 of its revenue in November, then the store's revenue in December was how many times the average (arithmetic mean) of its revenues in November and January?

(A) 1/4
(B) 1/2
(C) 2/3
(D) 2
(E) 4

E
Join the discussion
Source: — Problem Solving |

by Jay@ManhattanReview » Tue Jul 25, 2017 10:45 pm
AbeNeedsAnswers wrote:If a certain toy store's revenue in November was 2/5 of its revenue in December and its revenue in January was 1/4 of its revenue in November, then the store's revenue in December was how many times the average (arithmetic mean) of its revenues in November and January?

(A) 1/4
(B) 1/2
(C) 2/3
(D) 2
(E) 4

E
Say the revenues in November, December and January are N, D, and J, respectively.

Thus, we have,

N = 2D/5;
J = N/4 = (2D/5)/4 = D/10

Say the revenue in December was x times the average (arithmetic mean) of its revenues in November and January.

Thus, D = x*(N + J)/2

D = x*(2D/5 + D/10)/2

D = Dx*(2/5 + 1/10)/2

2 = 5x/10; D cancells

[spoiler]x = 4.[/spoiler]

The correct answer: E

Hope this helps!

Download free ebook: Manhattan Review GMAT Quantitative Question Bank Guide

-Jay
_________________
Manhattan Review GMAT Prep

Locations: New York | Singapore | Doha | Lausanne | and many more...

Schedule your free consultation with an experienced GMAT Prep Advisor! Click here.
Join the discussion

by [email protected] » Wed Jul 26, 2017 7:02 pm
Hi AbeNeedsAnswers,

This question can be solved by TESTing VALUES.

We're told two facts about a toy store's revenue:
1) The revenue in November was 2/5 of the revenue in December.
2) The revenue in January was 1/4 of the revenue in November.

We're asked to define how the revenue in December relates to the AVERAGE of the revenues in November and January.

Let's TEST the common-denominator of those two fractions: 20
IF...
December revenue = $20
November revenue = (2/5)($20) = $8
January revenue = (1/4)($8) = $2

The average of the November and January revenues is ($8+$2)/2 = $5. The December revenue ($20) is 4 times that average.

Final Answer: E

GMAT assassins aren't born, they're made,
Rich
Contact Rich at [email protected]
Image
Join the discussion

by Scott@TargetTestPrep » Mon Aug 14, 2017 1:10 pm
AbeNeedsAnswers wrote:If a certain toy store's revenue in November was 2/5 of its revenue in December and its revenue in January was 1/4 of its revenue in November, then the store's revenue in December was how many times the average (arithmetic mean) of its revenues in November and January?

(A) 1/4
(B) 1/2
(C) 2/3
(D) 2
(E) 4

E
We can let n = revenue in November, d = revenue in December, and j = revenue in January. We can create the following equations:

n = (2/5)d

j = (1/4)n

So, j = (1/4)(2/5)d = (1/10)d

We now determine that the average revenue for November and January is:

[(2/5)d + (1/10)d]/2

[(4/10)d + (1/10)d]/2

(5/10)d/2 = (1/4)d

Thus, the revenue in December is d/[(1/4)d] = 4 times the average revenue for November and January.

Answer: E

Scott Woodbury-Stewart
Founder and CEO
[email protected]

Image

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

ImageImage
Join the discussion