a bookstore sells new books for $15 each and used books for : Quant Question Archive [LOCKED] Check GMAT Club Decision Tracker for the Latest School Decision Releases http://gmatclub.com/AppTrack  It is currently 23 Jan 2017, 21:07 ### GMAT Club Daily Prep #### Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email. Customized for You we will pick new questions that match your level based on your Timer History Track Your Progress every week, we’ll send you an estimated GMAT score based on your performance Practice Pays we will pick new questions that match your level based on your Timer History #### Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here. ### Request Expert Reply # Events & Promotions ###### Events & Promotions in June Open Detailed Calendar # a bookstore sells new books for$15 each and used books for

 post reply Question banks Downloads My Bookmarks Reviews Important topics
Author Message
CEO
Joined: 21 Jan 2007
Posts: 2756
Location: New York City
Followers: 11

Kudos [?]: 860 [0], given: 4

a bookstore sells new books for $15 each and used books for [#permalink] ### Show Tags 22 Oct 2007, 09:15 This topic is locked. If you want to discuss this question please re-post it in the respective forum. a bookstore sells new books for$15 each and used books for $10 each. On every new book, the store makes a profit of$5 while on every used book, it makes a profit of $2. If on a given day the sales were$125, which of the following cannot be the profit on that day?

27
31
35
39
41
Senior Manager
Joined: 02 Aug 2007
Posts: 347
Location: Greater New York City area
Schools: Tuck, Ross (R1), Duke, Tepper, ISB (R2), Kenan Flagler (R2)
Followers: 3

Kudos [?]: 46 [0], given: 0

### Show Tags

22 Oct 2007, 10:08
E.

From the given information about sales,
15x + 10y =125.
So, 3x + 2y = 25

Also, from the given information about profits
5x + 2y = 27 or 31 or 25 or 39 or 41.

Lets take the first case : 5x + 2y = 27.
Solve this and the earlier sales eqn, we get x = 1, y = 11. The values of x and y fit well in to both the equations.

Test this for each of the 5 possibilities of value of profit. Its fits for each except for 5x + 2y = 41. If we solve this and sales eqn, we get x = 8. But if we substitute, x = 8 in either of the eqn. y is not an integer. So the answer is E.

Whats the OA ?
Manager
Joined: 18 Jun 2007
Posts: 55
Followers: 1

Kudos [?]: 5 [0], given: 0

### Show Tags

22 Oct 2007, 10:20
15x + 10y = 125
Max profit is when you sell max of X.
So, max x = 7. 7*15= 105 + 10y = 125, y =2
Thus, max profit is 7*5 + 2*2 = 39.

It can't be higher than 39, so 41 is impossible.
Director
Joined: 20 Aug 2007
Posts: 851
Location: Chicago
Schools: Chicago Booth 2011
Followers: 11

Kudos [?]: 97 [0], given: 1

### Show Tags

22 Oct 2007, 11:04
I get 41 profit is impossible as well.

N = new books sold
U = used books sold
P = profit

15N + 10U = 125
5N + 2U = P

combining equations (mult bottom eq by -3)

4U = 125-3P ----------> 125 - 4U = 3P

By pluggin in numbers, if you try 41 for P you get 125 - 4U = 122, which is impossible.
CEO
Joined: 21 Jan 2007
Posts: 2756
Location: New York City
Followers: 11

Kudos [?]: 860 [0], given: 4

### Show Tags

06 Dec 2007, 06:09
ben928 wrote:
15x + 10y = 125
Max profit is when you sell max of X.
So, max x = 7. 7*15= 105 + 10y = 125, y =2
Thus, max profit is 7*5 + 2*2 = 39.

It can't be higher than 39, so 41 is impossible.

Excellent approach

OA is E.
06 Dec 2007, 06:09
Display posts from previous: Sort by

# a bookstore sells new books for \$15 each and used books for

 post reply Question banks Downloads My Bookmarks Reviews Important topics

 Powered by phpBB © phpBB Group and phpBB SEO Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.