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If x books cost $5 each and y books cost $8 each, then the

by AAPL » Tue Aug 20, 2019 7:36 am

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If x books cost $5 each and y books cost $8 each, then the average (arithmetic mean) cost, in dollars per book, is equal to

A. \(\frac{5x+8y}{x+y}\)

B. \(\frac{5x+8y}{xy}\)

C. \(\frac{5x+8y}{13}\)

D. \(\frac{40xy}{x+y}\)

E. \(\frac{40xy}{13}\)

OA A
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by Jay@ManhattanReview » Tue Aug 20, 2019 9:27 pm
AAPL wrote:Official Guide

If x books cost $5 each and y books cost $8 each, then the average (arithmetic mean) cost, in dollars per book, is equal to

A. \(\frac{5x+8y}{x+y}\)

B. \(\frac{5x+8y}{xy}\)

C. \(\frac{5x+8y}{13}\)

D. \(\frac{40xy}{x+y}\)

E. \(\frac{40xy}{13}\)

OA A
Cost of x book = 5*x = $5x;
Cost of y book = 8*y = $8y

Total cost of (x + y) books = $(5x + 8y)

Thus, average (arithmetic mean) cost, in dollars per book = (5x + 8y)/(x + y)

The correct answer: A

Hope this helps!

-Jay
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by deloitte247 » Wed Aug 21, 2019 10:28 am
x books = $5
Total cost of x books = $5x
Total costs of y books = $8y
$$Arithmetic\ mean\ \left(average\right)=\frac{\left(total\ \cost\ of\ x\ books+total\ \cost\ of\ y\ books\right)}{sum\ of\ x\ +\ y}$$
$$Arithmetic\ mean\ \left(average\right)=\frac{$5x+$8y}{x\ +\ y}$$

Therefore, we have option A to be our correct answer.
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by Scott@TargetTestPrep » Sun Aug 25, 2019 5:27 pm
AAPL wrote:Official Guide

If x books cost $5 each and y books cost $8 each, then the average (arithmetic mean) cost, in dollars per book, is equal to

A. \(\frac{5x+8y}{x+y}\)

B. \(\frac{5x+8y}{xy}\)

C. \(\frac{5x+8y}{13}\)

D. \(\frac{40xy}{x+y}\)

E. \(\frac{40xy}{13}\)

OA A
Using the weighted average formula, we see that the average cost, in dollars per book, is:

(5x + 8y)/(x + y)

Answer: A

Scott Woodbury-Stewart
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by Brent@GMATPrepNow » Mon Aug 26, 2019 9:26 am
AAPL wrote:Official Guide

If x books cost $5 each and y books cost $8 each, then the average (arithmetic mean) cost, in dollars per book, is equal to

A. \(\frac{5x+8y}{x+y}\)

B. \(\frac{5x+8y}{xy}\)

C. \(\frac{5x+8y}{13}\)

D. \(\frac{40xy}{x+y}\)

E. \(\frac{40xy}{13}\)

OA A
Average cost per book = (TOTAL cost of all books)/(total number of books)

GIVEN: x books cost $5 each and y books cost $8 each
Cost of x books at $5 apiece = 5x
Cost of y books at $8 apiece = 8y
TOTAL cost of all books = 5x + 8y

TOTAL number of books = x + y

Average cost per book = (5x + 8y)/(x + y)

Answer: A

Cheers,
Brent
Brent Hanneson - Creator of GMATPrepNow.com
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