The following table gives the frequency distribution of the number of hours spent per week on activities that involve sports and/or exercise by a sample of 400 Americans. The numbers are consistent with the summary results from the Bureau of Labor Statistics’ American Time Use Survey (www.bls.gov/tus).
Hours per Week Number of People
0 to less than 3.5............ 34
3.5 to less than 7.0............ 92
7.0 to less than 10.5.......... 55
10.5 to less than 14........... 0 83
14.0 to less than 28.0........... 121
28.0 to less than 56.0........... 15
Find the mean, variance, and standard deviation.