Arithmetic mean and standard deviation of a certain normal distribution are 13 and 1.5. What value is exactly 2 standard deviations less than the mean?  Choices
A) 10.5	B) 10	C) 11.5	D) 12	E) 12.5
The value which is exactly two SD below the mean is: mean-2*SD=13-2*1.5= 
<gadget id="calculator">13-2*1.5</gadget>
<output>10</output>
10.   Answer: 10.
<result>B</result>
Arithmetic mean and standard deviation of a certain normal distribution are 13 and 1.5. What value is exactly 2 standard deviations less than the mean?