spriya wrote:

scthakur wrote:

mean +- 2.5 sd is from 12.5 to 27.5

Only number outside this range is 12. Hence, A.

I simply guessed through this question thought the value with max diff from mean is the answr

Can u tell me how u got the values 12.5 and 27.5

any calculations

spriya, read the question this way -->

If a certain sample of data has a mean of 20 and a standard deviation of 3, which of the following values is more than

2.5 (standard deviations) from the mean?

I hope now you will get how we get the answer