AAPL wrote:Official Guide

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. \(4\)

OA E

Since we have to deal with fractions and denominators of 2/5 and 1/4 are 5 and 4, let's assume that December revenue = 5*4 = $20;

Thus, November revenue = 2/5 of 20 = $8;

And, January revenue = 1/4 of 8 = $2;

Average of November and January revenues = (8 + 2)/2 = $5

Thus, December revenue ($20) is 20/5 = 4 times of average revenue of November and January ($5).

The correct answer: E

Hope this helps!

-Jay
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AAPL wrote:Official Guide

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. \(4\)

OA 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:

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

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

= (5/10)d/2

= (1/4)d

Since the average revenue for November and January is ¼ the December revenue, we see that December's revenue is 4 times the average revenue of November and January.

Alternative Solution:

We can let the revenue in November = 40, thus the revenue is December = 40/(2/5) = 40 x 5/2 = 100 and the revenue in January = 1/4 x 40 = 10.

We see that the average of the revenues in November and January is (40 + 10)/2 = 25 and December's revenue, 100, is 4 times the average revenue of November and January.

Answer: E