number of light bulbs

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Ad_Astra_Per_Aspera: Junior | Next Rank: 30 Posts; Posts: 15; Joined: Tue Jul 22, 2008 6:52 am; Thanked: 2 times

number of light bulbs

by Ad_Astra_Per_Aspera » Sat Jul 11, 2009 9:55 am

A number of light bulbs were purchased to illuminate a gym. However, only 2/3 of them were needed and 160 leftover light bulbs were returned. If only 60% of their cost, or $96, was reimbursed, how much money was spent on illuminating the gym?

A $160
B $320
C $360
D $372
E $384

I find the language of the question ambiguous. Also if you could put forward a quicker way to analyze and solve this question that would be great.

thanks

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Source: Beat The GMAT — Problem Solving | Sat Jul 11, 2009 9:55 am

abhinav85: Master | Next Rank: 500 Posts; Posts: 179; Joined: Mon Dec 29, 2008 4:41 am; Thanked: 2 times

by abhinav85 » Sat Jul 11, 2009 10:05 am

IMO E!!!

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scoobydooby: Legendary Member; Posts: 1035; Joined: Wed Aug 27, 2008 10:56 pm; Thanked: 104 times; Followed by:1 members

by scoobydooby » Sat Jul 11, 2009 10:27 am

i get E as well.

let there be x bulbs. 1/3 of the bulbs were returned, given 1/3*x=160
x=480 bulbs

badly worded, but i take 60% of the cost of the returned items were reimbursed.
0.60*C=96
=>C=160
cost of 160 returned items=160
=> cost of each bulb=$1

total amount spent on the purchase of 480 bulbs= $480
amount reimbursed =$96
=> net amount spent $480-$96=$384

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shibal: Master | Next Rank: 500 Posts; Posts: 345; Joined: Wed Mar 18, 2009 6:53 pm; Location: Sao Paulo-Brazil; Thanked: 12 times; GMAT Score:660

by shibal » Sat Jul 11, 2009 10:45 am

in a sc section i'd go with the stem, since it's not clear if it's the amount after the 1st purchase or if it's after we get the 96 dollars back... since we don't have 480 in the answer options, E is the rght one....