Arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 2.5. What value is exactly 2 standard deviations less than the mean?  Choose the correct choice from the following options:	A) 8.5	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*2.5=8.5.   8.5nswer: 8.5.
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Arithmetic mean and standard deviation of a certain normal distribution are 13.5 and 2.5. What value is exactly 2 standard deviations less than the mean?