A standard work week for hospital nurses is five 12-hour shifts. The following frequency table shows results from a survey of 130 registered nurses at area hospitals who  were asked how many 12-hour shifts they had worked during the past month:

Shifts x                                   Number of Nurses f(x)

20……………………………………            31

21……………………………………            46

22……………………………………            28

23……………………………………            15

24……………………………………            10

 Total = 130

a. Show the frequency bar chart for the data.

b. Compute the mean, the variance and the standard deviation for the data. 

c. Identify the median and the mode. 

d. Use vocabulary from the chapter to describe the shape of the distribution.