Numeric entry has always a number as Official Question

This is the standard of the GRE exam

This is a bad question for two reasons:
1) The relationship between List A and List B is unclear. Are the two lists identical, except for one additional value in List B. Or is it simply the case that List A has 80 numbers and list B has 81 numbers?

2) The GRE won't require you to calculate any standard deviations (unless the results are trivial, such as the standard deviation is 0, or we are looking for a "new" standard deviation after performing at the same operation on each value in a set.

What's the source of this question?

Hi,
I am also surprised when I meet this question. The source is from a GRE tutor, but he only gives me the answers to the question not how to solve it.

There are TONS of great (official) questions on this website. Unless you've answered all of them, I wouldn't bother with questions from other sources.

I do not think is an easy task solving more than 10,000 thousand questions

Carcass

the answer is supposed to be 8.944

SD is zero for the list A of 80 numbers so all the numbers are equally spaced assume it as x

average of these numbers plus 92 is 12 so (80x +92)/81 = 12
x is 11
now using the SD formula

(11-12)^2 + (11-12)^2 + ...... + (92-12)^2 =1 + 1 + ..... + 80^2 = 80 + 80^2 = 6480
divide it with 81 you get 80

square root it you get 8.944

Correct sir