The arithmetic mean and standard deviation of a certain normal distribution are 15.5 and 1.5, respectively. What value is exactly 2 standard deviations less than the mean?  Choose the correct choice from the following choices
A) 10.5  B) 11  C) 11.5  D) 12  E) 12.5

Rationale: "the value which isexactlytwo sd less than the mean is : mean - 2 * sd = 15.5 - 2 * 1.5 = 12.5 . answer : e ."
Answer: E