A call center is trying to better understand staffing requirements. It investigates the number of calls received during the evening shift and obtains the information given below. Construct a histogram of the data and comment on the key characteristics of the distribution. Construct a frequency polygon and compare it to the histogram. Which do you prefer and why?

Class Interval ......Frequency

10–under 20 ....... 9

20–under 30 ........ 7

30–under 40 .......10

40–under 50 ......... 6

50–under 60 .......13

60–under 70 .........18

70–under 80 ........15