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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## In a certain theater, the first row has 16 seats and the nex ##### This topic has expert replies Elite Legendary Member Posts: 3040 Joined: 24 Jul 2015 Location: Las Vegas, USA Thanked: 19 times Followed by:36 members ### In a certain theater, the first row has 16 seats and the nex by Max@Math Revolution » Tue Mar 15, 2016 5:50 pm In a certain theater, the first row has 16 seats and the next row has 2 more seats than previous row. If the last row has 64 seats, what is the total number of seats? A. 640 B. 720 C. 1,000 D. 1,200 E. 1,240 * A solution will be posted in two days. Math Revolution Finish GMAT Quant Section with 10 minutes to spare. The one-and-only World's First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy. Only$149 for 3 month Online Course
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by sandipgumtya » Thu Mar 17, 2016 9:02 am
We can apply AP series formula here.First term as 16 and last term 64.We get the no of terms as 25.Now the sum formula.
Sum=(25/2)*(2*16+24*2)=1000.Ans-C

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by Max@Math Revolution » Sat Mar 19, 2016 9:58 pm
In a certain theater, the first row has 16 seats and the next row has 2 more seats than previous row. If the last row has 64 seats, what is the total number of seats?

A. 640
B. 720
C. 1,000
D. 1,200
E. 1,240

A1=16, A2=16+2, A3=16+2*2,.....,An=16+(n-1)2=2n+14. In order make 2n+14=64, n should be 25. That is, there are 25 rows. Thus, in total, 25(16+64)/2=1,000 is derived. The answer is C.

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