From Chapter 5, a random sample of 20 purchases showed the following amounts (in $):
|
39.05
|
2.73
|
32.92
|
47.51
|
|
37.91
|
34.35
|
64.48
|
51.96
|
|
56.95
|
81.58
|
47.80
|
11.72
|
|
21.57
|
40.83
|
38.24
|
32.98
|
|
75.16
|
74.30
|
47.54
|
65.62
|
Recall that the mean was $45.26 and the standard deviation was $20.67.
a) What is the standard error of the mean?
b) How would the standard error change if the same size had been 5 instead of 20? (Assume that the sample standard deviation didn't change.)