The arithmetic mean and standard deviation of a certain normal distribution are 17.5 and 2.5, respectively. What value is exactly 2 standard deviations less than the mean?
Choose the correct choice: A) 10.5 B) 11 C) 11.5 D) 12 E) 12.5
Mean = 17.5   Two standard deviations is 2.5 + 2.5= 
<gadget id="calculator">2.5 + 2.5</gadget>
<output>5</output>
5.0   There could be two calues for this.   Mean + two standard deviations= 22.5   Mean - Two standard deviations = 12.5   Answer choice has 12.5 and so 12.5 is the answer.
<result>E</result>
The arithmetic mean and standard deviation of a certain normal distribution are 17.5 and 2.5, respectively. What value is exactly 2 standard deviations less than the mean?