If a certain sample of data has a mean of 23.0 and a standard deviation of 3.0, which of the following values is more than 2.5 standard deviations from the mean? Options.
A) 12.0  B) 13.5  C) 15.0  D) 23.5  E) 26.5
Value ismore than 2.5SDfrom the mean means that the distance between the mean and the value must be more than 2.5*SD=7.5. So the value must be either less than 23-7.5= 
<gadget id="calculator">23-7.5</gadget>
<output>15.5</output>
15.5or more than 23+7.5=30.5.   Answer: 15.0.
<result>C</result>
If a certain sample of data has a mean of 23.0 and a standard deviation of 3.0, which of the following values is more than 2.5 standard deviations from the mean?