The following frequency table shows the number of customers per day at a small restaurant.
Number of Customers Number of Days
0 - Under 20 12
20 - Under 40 22
40 - Under 60 16
60 - Under 80 21
80 - Under 100 19
What is the class width?
How many total days are there?
What is the relative frequency for the class 60 - Under 80?