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Set X has 5 integers: a, b, c, d, and e. If m is the mean [#permalink]
22 Feb 2012, 21:22

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A

B

C

D

E

Difficulty:

(N/A)

Question Stats:

100% (01:52) correct
0% (00:00) wrong based on 1 sessions

Set X has 5 integers: a , b , c , d , and e . If m is the mean and D , where D = \sqrt{\frac{(a-m)^2+(b-m)^2+(c-m)^2+(d-m)^2+(e-m)^2}{5}} , is the standard deviation of the set X , is D \gt 2 ?

a , b , c , d , and e are different integers m is an integer not equal to any elements of the set X

Strategy for reaching answer C. Can eliminate A B & D. Stuck between C & E. If testing numbers how to select appropriate numbers???????? how to be sure of the minimum range???

Set X has 5 integers: a , b , c , d , and e . If m is the mean and D , where D = \sqrt{\frac{(a-m)^2+(b-m)^2+(c-m)^2+(d-m)^2+(e-m)^2}{5}} , is the standard deviation of the set X , is D \gt 2 ?

a , b , c , d , and e are different integers m is an integer not equal to any elements of the set X

Strategy for reaching answer C. Can eliminate A B & D. Stuck between C & E. If testing numbers how to select appropriate numbers???????? how to be sure of the minimum range???

Let me note though that I wouldn't worry about this question at all, since you won't see anything like this on the real test.

Generally for the GMAT you only need to understand the concept of SD: you won't be asked to actually calculate the standard deviation of a set on the GMAT. So, what is the main thing you should know about it? Standard deviation shows how much variation there is from the mean, how widespread a given set is. So, a low standard deviation indicates that the data points tend to be very close to the mean, whereas high standard deviation indicates that the data are spread out over a large range of values.