Find the variance and standard deviation of the probability distribution constructed in Try It Yourself 2.

a. For each value of x, find the square of the deviation from the mean and multiply that value by the corresponding probability of x.

b. Find the sum of the products found in part (a) for the variance.

c. Take the square root of the variance to find the standard deviation.

d. Interpret the results.

Frequency Distribution

Sales per day, x         Number of days, f

0 ………………………………...      16

1 ………………………………...      19

2 ………………………………...      15

3 ………………………………...      21

4 ………………………………...       9

5 ………………………………...      10

6 ………………………………...       8

7 ………………………………...       2