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Mean

by SaraLotfy » Thu Sep 19, 2013 12:14 am
If set R contains the consecutive integers from -5 to -1. what is the mean of set R?
A) -5
B) -3
C) 0
D) 3
E) 5
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by theCodeToGMAT » Thu Sep 19, 2013 12:20 am
Mean would be [spoiler][/spoiler]
Since
( -5 + -4 + -3 + -2 + -1)
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5

= -3
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by ganeshrkamath » Thu Sep 19, 2013 2:28 am
SaraLotfy wrote:If set R contains the consecutive integers from -5 to -1. what is the mean of set R?
A) -5
B) -3
C) 0
D) 3
E) 5
This is an easy one.
Mean = sum/(number of terms)
= ((-5) + (-4) + (-3) + (-2) + (-1))/5
= (-15)/5
= -3

Choose B

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by Brent@GMATPrepNow » Thu Sep 19, 2013 7:28 am
SaraLotfy wrote:If set R contains the consecutive integers from -5 to -1. what is the mean of set R?
A) -5
B) -3
C) 0
D) 3
E) 5
Since consecutive numbers are equally spaced, we can use two other approaches:

Approach #1
There's a nice rule that says, "In a set where the numbers are equally spaced, the mean will equal the median."
The numbers are {-5, -4, -3, -2, -1}
So, the mean = median = -3

Approach #2
There's another nice rule that says, In a set where the numbers are equally spaced, the mean = (largest value + smallest value)/2
So, for this question, the mean = [(-1) + (-5)]/2 = -3

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