Standard Deveation

[gmat_nidhesh]

operator..1:00-2:00...2:00-3:00.....3:00-4:00.....4:00-5:00
opt A..........3..............7................7...... ..........3
opt B..........4..............5................5...... ..........6
opt C..........8..............2................5...... ..........5
opt D..........6..............4................4...... ..........6
opt E..........3..............4................5...... ..........8


Q1. 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 SD of the number of calls reciebed during these 4 periods the least ?
1) A
2) B
3) C
4) D
5) E

SPOILER: B

[AKAMBA]

Just eyeballing it, we can see that the mean is the same for all of them (i.e. 5). But it looks like the numbers in opt B are the most closely packed together.

[rajatmeh]

Yes agree with AKAMBA's reasoning.