Approximate the sample statistics given the following frequency distribution.

Hint: Use calculator to calculate mean, standard deviation.

Class Frequency

0 - 19 10

20 - 39 10

40 - 59 12

60 - 79 19

80 - 99 15

a) Find class midpoints. List your midpoints on ascending order, use commas to separate the midpoints.

Midpoints are:

b) Approximate the sample mean. Round the sample mean to 4 decimal places.

x =

c) Approximate the sample standard deviation. Round the sample standard deviation to 4 decimal places.

s =

d) Approximate the sample variance. Round the sample variance to 4 decimal places.

s =