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JeetGulia: Senior | Next Rank: 100 Posts; Posts: 66; Joined: Mon Jun 14, 2010 4:46 am; Thanked: 3 times

by JeetGulia » Mon Sep 13, 2010 4:13 pm

If the terms of s sequence are T1, T2, T3..Tn, what is the value of n?

a) The sum of the n terms is 3, 124.
b) the average mean of the n terms is 4.

Ans C

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Source: Beat The GMAT — Data Sufficiency | Mon Sep 13, 2010 4:13 pm

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Rahul@gurome: GMAT Instructor; Posts: 1179; Joined: Sun Apr 11, 2010 9:07 pmFollowed by: 88 members; Location: Milpitas, CA; Thanked: 447 times

by Rahul@gurome » Mon Sep 13, 2010 5:38 pm

(1) T1 + T2 +...+ Tn = 3124, but this is not sufficient to find n.
So, (1) is NOT SUFFICIENT.

(2) (T1 + T2 +...+ Tn)/n = 4 implies T1 + T2 +...+ Tn = 4n.
So, (2) is NOT SUFFICIENT.

Combining (1) and (2), 3124 = 4n, solving which we get the value of n.

The correct answer is [spoiler](C)[/spoiler].

Rahul Lakhani
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