Find the Number of Standard Deviations from the Mean

Multiple Choice

Find the number of standard deviations from the mean. Round your answer to two decimal places.
-The annual snowfall in a town has a mean of 39 inches and a standard deviation of 10 inches. Last year there were 64 inches of snow. How many standard deviations from the mean is that?

A) 0.45 standard deviations above the mean
B) 0.45 standard deviations below the mean
C) 2.50 standard deviations above the mean
D) 2.50 standard deviations below the mean