If a sample of data has mean of 21 and SD of 3, which of the following values is more than 2.5 SDs ...

If a sample of data has mean of 21 and SD of 3, which of the following values is more than 2.5 SDs from the mean?

Quiz

Answer/Solution

a. 12

Steps/Work

Value ismore than 2.5SDfrom the mean means that the distance between the mean and the value must be more than 2.5SD=7.5. So the value either <21-7.5=13.5 or >21+7.5=28.5.
Answer: A.