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Re: x, y and z are positive. If x percent of y is z
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29 Mar 2017, 05:57

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GMATPrepNow wrote:

x, y and z are positive. If x percent of y is z, and z percent of x is y, then what is x² percent of 1/10?

A) 1/100 B) 1/10 C) 1 D) 10 E) 100

Here's one approach:

x percent of y is z So (x/100)(y) = z Simplify: xy/100 = z

z percent of x is y So (z/100)(x) = y Simplify: xz/100 = y

Multiply the two equations to get: (xy/100)(xz/100) = (z)(y) Simplify: x²yz/10,000 = yz Divide both sides by yz to get: x²/10,000 = 1 This means x² = 10,000

What is x² percent of 1/10? In other words, (x²/100)(1/10) = ? Replace x² with 10,000 to get: (10,000/100)(1/10) = 10,000/1,000 = 10