Data Sufficiency

VIGNESHWARR wrote:If a wire 27 meters long is cut into three pieces of three different lengths, what is the length of the longest piece?

1.The length of the longest piece is twice the length of the shortest piece.

2.The sum of the lengths of the two shorter pieces is 15 meters.

Target question: What is the length of the longest piece?

Let S = length of shortest piece
Let M = length of medium-length piece
Let L = length of longest piece

Given: The wire 27 meters long is cut into three pieces of three different lengths
In other words, S + M + L = 27
Also, S < M < L

Statement 1: The length of the longest piece is twice the length of the shortest piece.
There are several scenarios that meet this condition. Here are two:
Case a: the lengths are 6, 9, 12, in which case the longest piece has length 12
Case b: the lengths are 6.5, 7.5, 13, in which case the longest piece has length 13
Since we cannot answer the target question with certainty, statement 1 is NOT SUFFICIENT

Statement 2: The sum of the lengths of the two shorter pieces is 15 meters.
In other words, S + M = 15
We already knew that S + M + L = 27, so replace S + M with 15, to get:
15 + L = 27
So, L must equal 12
Since we can answer the target question with certainty, statement 2 is SUFFICIENT

Answer = B

Cheers,
Brent