azelastine wrote:

A rectangular pasture has fence posts along every side at 15-foot intervals. If there are 6 fence posts along the length of the pasture and the perimeter of the pasture is 240 feet, how many fence posts would surround this pasture if the width were doubled? (Assume that the space taken up by the fence posts is negligible.)

A) 14

B) 16

C) 20

D) 22

E) 24

Think of it this way:

6 fence posts along the length means 1 at the beg and 1 at the end with 4 in the middle and in all, five 15-foot gaps, a total of 75 feet in them. The other length will be the same 6 posts with 75 feet between them.

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Since the perimeter of the pasture is 240 feet, and combined length is 150 feet, the combined width is 90 feet which means each width is 45 feet. Hence, in all we will have 4 posts on the width including the ends.

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If we double the width, we get 90 feet width which needs 7 posts (including the ends)

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In all, we have 6 + 6 + 5 + 5 = 22 posts

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Karishma

Veritas Prep GMAT Instructor

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