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Mean of a set

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Mean of a set [#permalink]

17 Nov 2011, 16:39

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Question Stats:

60% (02:06) correct

40% (00:35) wrong

based on 0 sessions

What is the minimum percentage increase in the mean of set X {-4, -1, 0, 6, 9} if its two smallest elements are replaced with two different primes?
(A) 25%
(B) 50%
(C) 75%
(D) 100%
(E) 200%

OA is not provided. But I got D. Is D the right answer?
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Re: Mean of a set [#permalink]

17 Nov 2011, 17:29

I do also. The given set comes to an average of 2 and the smallest *different* primes you can substitute would be 2 and 3. That would bring the new average to 4. Of course, 4 is 200% of 2, but it's just a 100% increase.

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Re: Mean of a set [#permalink]

18 Nov 2011, 01:37

I go with D....

1st average is 2
2nd average is 4

percentage increase:
4-2/2*100= 2/2*100=1*100=100%

hope that helps
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Re: Mean of a set [#permalink] 18 Nov 2011, 01:37

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