The costs per load (in cents) of 35 laundry detergents tested by a consumer organization are shown

Question:

The costs per load (in cents) of 35 laundry detergents tested by a consumer organization are shown here.
Class limits Frequency
13–19 ..........2
20–26 ..........7
27–33 ........12
34–40 ..........5
41–47 ..........6
48–54 ..........1
55–61 ..........0
62–68 ..........2
Find the variance and standard deviation.