PS.... HELP NEEDED!!!

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PS.... HELP NEEDED!!!

by AIM TO CRACK GMAT » Wed Oct 24, 2012 12:37 am
A bookstore has a shelf that contains biographies which normally sell for $20 each and mysteries that normally sell for $12 each. During a sale, the biographies and mysteries are discounted at different rates so that a customer saves a total of $19 from the normal price by buying 5 discounted biographies and 3 discounted mysteries. If the sum of the discount rates for the two types of books is 35 percent, wha is the discount rate on mysteries?

(A) 9
(B) 10
(C) 13
(D) 22
(E) 25


OA= E
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by GMATGuruNY » Wed Oct 24, 2012 2:34 am
AIM TO CRACK GMAT wrote:A bookstore has a shelf that contains biographies which normally sell for $20 each and mysteries that normally sell for $12 each. During a sale, the biographies and mysteries are discounted at different rates so that a customer saves a total of $19 from the normal price by buying 5 discounted biographies and 3 discounted mysteries. If the sum of the discount rates for the two types of books is 35 percent, wha is the discount rate on mysteries?

(A) 9
(B) 10
(C) 13
(D) 22
(E) 25
We can plug in the answers, which represent the discount rate on mysteries.
The regular price of a mystery is $12.
The total amount saved by the customer is $19 -- an INTEGER value.
Only answer choice E will yield an integer value for the amount saved on mysteries.

Answer choice E: 25%
Amount saved on 3 mysteries discounted at 25% = 3 * .25(12) = 9.
Since the sum of the discount rates is 35, the discount rate on biographies = 35-25 = 10%.
Amount saved on 5 biographies discounted at 10% = 5 * .1(20) = 10.
Total savings = 9+10 = 19.
Success!

The correct answer is E.
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