Question

The average amount of a purchase at a pipe and tobacco store is $2.12. The standard deviation is $.45. 99.7% of the amount of purchase far between what two prices?

Answer 1

The empirical rule states that 99.7% of the data values will fall within 3 standard deviations of the mean. To calculate "within 3 standard deviations," you need to subtract 3 standard deviations from the mean, then add 3 standard deviations to the mean. That will give you the range for 99.7% of the data values.

2.12−3*0.45=0.77
and 2.12+3⋅0.45=3.47
The range of numbers is 0.77 to 3.47

99.7% of the amount of purchase far between $ 0.77 to $ 3.47