Hi zxcvbnmas,

Standard Deviation is a relatively rare category in the Quant section, although you're like to be tested on it 1 time on Test Day. You'll never be asked to calculate SD though, so you really just need to learn the basic 'concepts' behind it.

Here, we're told two things about a group of numbers:

1) The average of the group is 60

2) The standard deviation of the group is 12

If you go 1 SD "up" from the average, you hit.....60+12 = 72

If you go 1 SD "down" from the average, you hit.....60-12 = 48

If you go 2 SDs "up" from the average, you hit.....60+2(12) = 84

If you go 2 SDs "down" from the average, you hit.....60-2(12) = 36

Etc.

Here, we're asked for the number that is EXACTLY 1.75 SDs above the mean....

1.75 SDs "up" would be.....60 + 1.75(12) = 81

Final Answer:

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Rich

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