Arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 0.5. What value is exactly 2 standard deviations less than the mean?  Choose the correct answer
A) 10.5  B) 11  C) 11.5  D) 12  E) 12.5
The value which is exactly two SD below the mean is: mean-2*SD=13.5-2*0.5=12.5.   Answer: 12.5.
<result>E</result>
Arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 0.5. What value is exactly 2 standard deviations less than the mean?