From section 8-3.
8. Commute Time to Work A survey of 15 large
U.S. cities finds that the average commute time one way is 25.4
minutes. A chamber of commerce executive feels that the commute in
his city is less and wants to publicize this. He randomly selects 25
commuters and finds the average is 22.1 minutes with a standard
deviation of 5.3 minutes. At a significance value of 0.10, is he
correct?
12. Income of College Students’ Parents A large university
reports that the mean salary of parents of an entering class is
$91,600. To see how this compares to his university, a president
surveys 28 randomly selected families and finds that their average
income is $88,500. If the standard deviation is $10,000, can the
president conclude that there is a difference? At α = 0.10, is he
correct?
From section 8-4.
6. Stocks and Mutual Fund Ownership It has been found that
50.3% of U.S. households own stocks and mutual funds. A random
sample of 300 heads of households indicated that 171 owned some type
of stock. At what level of significance would you conclude that this
was a significant difference?
20. Foreign Languages Spoken in Homes Approximately 19.4% of
the U.S. population 5 years old and older speaks a language other
than English at home. In a large metropolitan area it was found that
out of 400 randomly selected residents over 5 years of age, 94 spoke
a language other than English at home. Is there sufficient evidence
to conclude that the proportion is higher than the national
proportion? Justify with a P-value.