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A jar contains exactly 10 dimes and x quarters and

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A jar contains exactly 10 dimes and x quarters and [#permalink] New post 05 Dec 2017, 13:01
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Question Stats:

87% (00:26) correct 12% (01:38) wrong based on 8 sessions
A jar contains exactly 10 dimes and x quarters and no other coins. If a coin is randomly selected from the jar, the probability that a quarter is selected is 0.6. What is the value of x.

A. 5
B. 6
C. 8
D.12
E. 15
[Reveal] Spoiler: OA

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Re: A jar contains exactly 10 dimes and x quarters and [#permalink] New post 05 Dec 2017, 18:03
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Not pretty sure if my reasoning is forthright

But we know that the probability is established as follows : 0,6 = # number of quarters / total of dimes and quarters in the jar.
Since we know that x = quarters and the dimes are exactly 10 we can replace as follows:
0,6 = x / 10 + x
We simply cross multiply
0,6 (10 + x) = x
6 + 0,6x = x
6 = x - 0,6x
6= 0,4x
X = 15

So answer E
Re: A jar contains exactly 10 dimes and x quarters and   [#permalink] 05 Dec 2017, 18:03
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A jar contains exactly 10 dimes and x quarters and

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