Standard deviation

[lordpapi63]

the arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 1.5 respectively. What value is exactly 2 standard deviations less than the mean?

10.5

11.0

11.5

12.0

12.5

[john1234]

The answers is A.
10.5

[shrikantkamble]

Arithmatic mean A.M. = 13.5
S.D = 1.5
2 standard deviation less than mean.
= 13.5 - 2*1.5
= 13.5 - 3.0
=10.5

Answer A 10.5 is correct answer