Heights for men are distributed according to a Normal model, with an average of 69 inches and a standard deviation of 3
inches. The tallest 30% of men will be at what height or taller? Round your answer to the nearest hundredth (two decimal
places), if necessary.
An MP3 manufacturer claimsthat 65% of teenagers 13 to 16 years old have their own MP3 players.
A researcher wishes to test the claim and selects a random sample of 80 teenagers. She finds that
57 have their own MP3 players. At � = 0.05, should the claim be rejected?
The average credit card debt for a recent year was $9205. Five years earlier the average credit card
debt was $6618. Assume sample sizes of 35 were used and the population standard deviations of
both samples were $1928. Find the 95% confidence interval of the difference in means.