Expert: Sherry Wallin - 6/22/2011

Question
The mean = 32.3 and standard deviation of the data is:6.3
---> Calculate the percent of sales, to the nearest whole number that are:
1) Within one standard deviation of the mean.
2) Within two standard deviation of the mean.

Answer
Hi Andrea~

There is a rule called the "Empirical Rule" for normal distributions or bell-shaped distributions and it says:
68% of the data will fall within one standard deviation of the mean
95% of the data will fall within two standard deviations of the mean and
99.7% of the data will fall within three standard deviations of the mean

For your question all you have to do is say that about 68% of the sales are within one standard deviation and that 95% of the sales are within two standard deviations of the mean.

Math Prof


***I answered the question the way it was asked but maybe what you wanted is that 68% of the sales will be between 26 and 38.6
and 95% of the sale will be between 19.7 and 44.9, while 99.7% of the sale will be between 13.4 and 51.2

Math Prof updated 7-7-11