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# What is the value of

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What is the value of [#permalink]  04 Feb 2018, 15:30
Expert's post
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Question Stats:

99% (01:12) correct 0% (00:00) wrong based on 7 sessions

What is the value of $$\frac{3}{5} (\frac{5}{8} - 4)$$?

A. $$\frac{- 81}{40}$$

B. $$\frac{- 3}{20}$$

C. $$\frac{3}{20}$$

D. $$\frac{4}{9}$$

E. $$\frac{81}{40}$$

Kudo for the right solution and explanation
[Reveal] Spoiler: OA

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Joined: 15 Jan 2018
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Re: What is the value of [#permalink]  04 Feb 2018, 19:52
1
KUDOS
McGraw-Hill questions are terrible. It's just too easy to eliminate based purely on answer choices. But let's do it anyway for practice. If you look inside the parenthesis, you see 5/8 - 4. Don't just robotically start cross-multiplying: think to yourself, how can I eliminate answers? 5/8 - 4 will get us a negative number right? This negative is then multiplied by 3/5, which is a positive, which means we'll get a negative number. So C, D, and E are out.

A and B are pretty different in size, so we can use that. Rather than actually doing the math, let's eyeball things. Let's pretend 5/8 is 1/2. So 1/2 - 4 is -3.5. If we multiply that by 3/5, well basically I don't want to, so let's pretend 3/5 is about 1/2 again. So then what's 1/2 of -3.5? It's -1.75, which is in the ballpark of A, and nowhere near B. So it's A. We did some pretty rough estimating, but that was ok in this case since the answers were so far apart. But if they'd been pretty close, which I think is more likely on the GRE, we would've had to actually do the math.
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Manager
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Re: What is the value of [#permalink]  25 Feb 2018, 04:25
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Why is this a medium question? It's quite easy actually. We work with what is inside the bracket: 5/8 - 4 = -27/8 then multiplying by 3/5 will give -81/40.
Re: What is the value of   [#permalink] 25 Feb 2018, 04:25
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