Variance & standard deviation of grouped frequency data

The following frequency table summarizes the ages of 100 shoppers at the local grocery store. Calculate the sample varianceand standard deviationfor this dataset. Please show your work in Excel.

Age of the shopper Frequency
15-25 15
25-35 30
35-45 25
45-55 15
55-65 10
65-75 5

This solution is comprised of a step-by-step explanation of finding the sample variance and standard deviation from a grouped frequency distribution.