What is the minimum percentage increase in the mean of set X

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What is the minimum percentage increase in the mean of set X [#permalink]

26 Jan 2012, 12:32

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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%

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Re: minimum percentage increase [#permalink]

26 Jan 2012, 12:39

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rohitgoel15 wrote:

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%

Mean of X is (-4-1+0+6+9)/5=2;

In order the increase to be minimal we should replace two smallest elements of X, which are -4 and -1, with two smallest primes, which are 2 and 3. Hence our new set will be {2, 3, 0, 6, 9} --> new mean is (2+3+0+6+9)/5=4.

Percent increase=(4-2)/2*100=100%.

Answer: D.
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Re: What is the minimum percentage increase in the mean of set X [#permalink]

26 Mar 2012, 09:10

hi Bunuel,

request to let me if two smallest primes numbers can be negative?
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eshwar

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Re: What is the minimum percentage increase in the mean of set X [#permalink]

26 Mar 2012, 09:18

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pappueshwar wrote:

hi Bunuel,

request to let me if two smallest primes numbers can be negative?

Only positive numbers can be primes, so the smallest prime is 2.

Hope it helps.
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Re: What is the minimum percentage increase in the mean of set X [#permalink]

01 Mar 2013, 03:09

1 is not a prime number, got to know it now..... was considering it & made the answer wrong

Re: What is the minimum percentage increase in the mean of set X [#permalink] 01 Mar 2013, 03:09

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What is the minimum percentage increase in the mean of set X

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What is the minimum percentage increase in the mean of set X

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