Constructing Confidence Intervals In Exercises 21 and 22, use the figure, which

ID: 3160614 • Letter: C

Question

Constructing Confidence Intervals

In Exercises 21 and 22, use the

figure, which shows the results of a survey in which 1044 adults from the

United States, 871 adults from Great Britain, 1097 adults from France, and

1003 adults from Spain were asked whether they consider air travel to be safe.

(Source: Harris Interactive)

Do You Consider Air Travel

to Be Safe?

United States 69%

Great Britain 72%

France 62%

Spain 75%

21. Air Travel

Construct a 99% confidence interval for the population

proportion of adults who consider air travel to be safe for

(a) the United States.

(b) Great Britain.

(d) Spain.

The 99% confidence interval for the population proportion of adults who consider air travel to be safe for the United States is:

p^+/-z(0.99)*root over p^(1-p^)/n

=0.69+/-2.58*root over 0.69*(1-0.69)/1044

=0.69+/-0.04

=(0.65,0.73)

The 99% confidence interval for the population proportion of adults who consider air travel to be safe for the Great Britain is:

p^+/-z(0.99)*root over p^(1-p^)/n

=0.72+/-2.58*root over 0.72*(1-0.72)/871

=0.72+/-0.04

=(0.68,0.76)

Using the above formula calculate the CI for Spain and France.

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