Question

a. The number of hours of sleep per night that adults in the United States is normally distributed with a mean of 6.8 hours and a standard deviation of 1.4 hours. If the recommended amount of sleep is 7 hours, what proportion of US adults are getting less than that amount of sleep? Round to the nearest ten-thousandth.

b. The number of hours of sleep per night that adults in the United States is normally distributed with a mean of 6.8 hours and a standard deviation of 1.4 hours. Out of 100 US adults, how many would you expect to get between 8 and 9 hours of sleep? Round to the nearest whole number. We would expect ___ adults to get between 8 and 9 hours of sleep.

c.The number of hours of sleep per night that adults in the United States is normally distributed with a mean of 6.8 hours and a standard deviation of 1.4 hours. What number of hours of sleep is at the 30th percentile? Round to the nearest ten-thousandth (4 decimal places).___ hours is at the 30th percentile.

d. The number of hours of sleep per night that adults in the United States is normally distributed with a mean of 6.8 hours and a standard deviation of 1.4 hours. Would it be considered unusual for a person to get at least 9 hours of sleep? Why or why not?

It ["would not", "would"] be unusual since the probability is ["greater than", "less than", "equal to"] 0.05.

e. The number of hours of sleep per night that adults in the United States is normally distributed with a mean of 6.8 hours and a standard deviation of 1.4 hours. A simple random sample of 100 people is selected. What is the probability that the mean of the sample is greater than 7 hours? Round to the nearest ten-thousandth

Answer 1