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PaperTest GMAT - Numbers/Sets problem

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PaperTest GMAT - Numbers/Sets problem

by oks » Fri Sep 05, 2008 3:00 pm
For the positive numbers, n, n+1, n+2, n+4, and n+8, the mean is how much greater the median?

Answ: 1

My approach: let n=1, n+1=2, n+2 = 3, n+4 = 5, n+8 = 9
So median = 3
mean ( i assumed mean of the set) = (1+9) / 2 = 5
Difference = 5-3 = 2
Answer then = n+1 = 2

On the other hand, if i calculate mean as avg (1+2+3+5+9) / 5 = 4
Difference = 4 - 3 = 1
Answer = 1

Could someone explain his/her approach? What am I missing?

Thanks!!!
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Re: PaperTest GMAT - Numbers/Sets problem

by parallel_chase » Fri Sep 05, 2008 3:12 pm
oks wrote:For the positive numbers, n, n+1, n+2, n+4, and n+8, the mean is how much greater the median?

Answ: 1

mean ( i assumed mean of the set) = (1+9) / 2 = 5
Wrong way of calculating mean.
On the other hand, if i calculate mean as avg (1+2+3+5+9) / 5 = 4
Correct way of calculating mean.


Mean of the set = Average of the set

Hope its clear.
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by sumithshah » Sat Sep 06, 2008 11:35 am
Your method of calculating mean is incorrect because that is used to calculate only for consecutive numbers - these numbers are clearly not consecutive
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check this

by rafofoa » Sat Sep 06, 2008 2:28 pm
the median is n+2,
the mean = n+n+1+n+2+n+4+n+8/5
= 5n+15/5
=n+3

let assume n=5, then the mean n+3=8; the median n+2 =7
the mean is therefore 1 greater than the median.
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by sameeranpanda » Sun Sep 07, 2008 9:32 am
the median is n+2,
the mean = n+n+1+n+2+n+4+n+8/5
= 5n+15/5
=n+3

Mean - Median = n+3 - n - 2 = 1.

The mean is 1 greater than the median
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