The table shows the number of calls received by each of five operators

Question

GMAT_PS_PREP_T2_39.png The table shows the number of calls received by each of five operators during each of 4 one-hour periods. For which operator was the standard deviation of the numbers of calls received during these 4 periods the least? A. Operator A B. Operator B C. Operator C D. Operator D E. Operator E

CareerGeek · Answer

Operator A --> 3, 7, 7, 3: Mean = 5
Operator B --> 4, 5, 5, 6: Mean = 5
Operator C --> 8, 2, 5, 5: Mean = 5
Operator D --> 6, 4, 4, 6: Mean = 5
Operator E --> 3, 4, 5, 6: Mean = 5

Deviations from Mean:
Operator A --> 3-5, 7-5, 7-5, 3-5 --> -2, 2, 2, -2
Operator B --> 4-5, 5-5, 5-5, 6-5 -->  -1, 0, 0, 1 
Operator C --> 8-5, 2-5, 5-5, 5-5 --> 3, -3, 0, 0
Operator D --> 6-5, 4-5, 4-5, 6-5 --> 1, -1, -1, 1
Operator E --> 3-5, 4-5, 5-5, 6-5 --> -2, -1, 0, 1

We can clearly see Operator B is least deviated from Mean value

IMO Option B

Archit3110 · Answer

mean value for each operator is 5 
and the least variation along mean is observed for operator B ; 
IMO B

ScottTargetTestPrep · Answer

We notice that the sum for each operator is 20; therefore, the mean number of calls for each operator is 5.

Since the standard deviation is a measure of how far data points are from the mean, we should look for the row with the values closest to 5.

Operator B has two calls equal to the mean, and two other calls that are pretty close to the mean. All the other operators either have no calls equal to the mean, or have other calls that are far away from the mean (or both). Thus, Operator B has the smallest standard deviation.

Answer: B

LoneSurvivor · Answer

To find the least we have to find out the least dispersed set , B's numbers are least dispersed

Hence B

bumpbot · Answer

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The table shows the number of calls received by each of five operators

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The table shows the number of calls received by each of five operators

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