Passengers on long airline flights may develop deep vein thrombosis (DVT), potentially dangerous blood clots. Although most blood clots in the bloodstream dissolve naturally, travelers on long flights...

Passengers on long airline flights may develop deep vein thrombosis (DVT), potentially dangerous blood clots. Although most blood clots in the bloodstream dissolve naturally, travelers on long flights have three times the risk of developing a blood clot. In a research study of people who traveled frequently as part of their job, 22 of 8755 developed a blood clot within eight weeks of a long flight.

 a. Find a 90% confidence interval for the true proportion of passengers on long flights who develop DVT within eight weeks of a long flight.

b. Is there any evidence to suggest this proportion is greater than 0.5%? Justify your answer.

People who watch multiple DVDs or several online TV episodes in a row are indulging in binge-watching. Most experts agree that this is mostly a harmless, enjoyable addiction. In a recent survey of 2693 U.S. adults with Internet access, 1670 watch multiple TV episodes back to back.48

a. Find a 99% confidence interval for the true proportion of adults with Internet access who watch multiple TV episodes back to back.

b. Find the sample size necessary to construct a 99% confidence interval with a bound on the error of estimation of 0.02.