Sleep apnea is a disorder in which there are pauses in breathing during sleep. People with this condition must wake up frequently to breathe. In a sample of 427 people aged 65 and over, 104 of them had sleep apnea.

a. Find a point estimate for the population proportion of those aged 65 and over who have sleep apnea.

b. Construct a 99% confidence interval for the proportion of those aged 65 and over who have sleep apnea.

c. In another study, medical researchers concluded that more than 9% of elderly people have sleep apnea. Based on the confidence interval, does it appear that more than 9% of people aged 65 and over have sleep apnea? Explain.