Question

A survey asked 1000 randomly selected recently retired people how many people, including themselves, are in a family tree that begins with their parents. Let X represent the number of people. The table below shows the probability distribution of the data. Find the mean and the standard deviation of the probability distribution using Excel.

x   P(x)
1   0.001
2   0.001
3   0.005
4   0.016
5   0.012
6   0.018
7   0.039
8   0.046
9   0.056
10   0.059
11   0.057
12   0.068
13   0.044
14   0.056
15   0.061
16   0.047
17   0.049
18   0.049
19   0.034
20   0.039
21   0.021
22   0.028
23   0.034
24   0.014
25   0.035
26   0.014
27   0.014
28   0.02
29   0.014
30   0.007
31   0.009
32   0.01
33   0.002
34   0.007
35   0.002
36   0.008
37   0.002
38   0.002

Answer 1