Using the chart from in the example in which we found the mean number of trips lasting five nights or more that American adults take per year, find the variance and standard deviation of the distribution.

Number of trips, X

0

1

2

3

4

Probability P(X)

0.06

0.70

0.20

0.03

0.01

Recall that the mean number of trips lasting more than five nights or more per year taken by American adults is __________.

Use the distribution in vertical columns finding X P(X) and X² P(X) for each outcome, X, and probability, P(X), then summing the columns and using the results in the formula.

X

P(X)

X P(X)

X² P(X)

0

0.06

1

0.70

2

0.20

3

0.03

4

0.01

Totals

= _______________________ = _______

.