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# GRE Brain Twister: Non-Standard Deviations

Set A consists of five positive numbers. SAT B consists of the square roots of each of the five numbers from Set A. If the standard deviation of Set B > standard deviation of Set A, which of the following must be true?

I. The range of the numbers in Set A is greater than 1

II. At least one of the numbers in Set A is less than 1

III. The range of Set A > Set B

(A) I only

(B) III only

(C) I and III

(D) I and II

(E) II only

### 5 Responses to GRE Brain Twister: Non-Standard Deviations

1. Reena February 9, 2016 at 10:50 pm #

Option E

2. keerthi December 26, 2015 at 5:22 am #

option :A
Range of set A has to be greater than 1 the reasons are:
1)Set A has all positive numbers.
2)It cannot have all zeros,if so the square of these number would be zero too and the S.D of both would be same.
3)I think it is not necessary that at least one should be zero and all 4 numbers equal to zero will be valid for this choice which would be wrong.
4)The S.D of B>S.D of A so the range of B>range of A.

3. ritesh December 23, 2015 at 8:56 pm #

4. alwaysArijit December 23, 2015 at 6:40 pm #

A. I only

5. kase December 23, 2015 at 4:14 pm #

hmm SAT B?

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