Part 1) Amount of Sleep (10 points)

A sleep study administered to US adults showed that the amount of sleep (in hours) they get in a 24-hour period is normally distributed with a mean of 6.5 hours and a standard deviation of 1.25 hours. Use normal probability calculations to answer the follwing questions.

Show your calculator functions to receive full credit. Round your answers to 4 decimals.

A.(no pts)

. How many hours of sleep did you get last night (round to nearest quarter of an hour)?

____________

. Ask an adult friend or a family member how many hours of sleep he/she got last night (round to nearest quarter of an hour). Report below. Make sure it is different than your sleep amount.

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B.(2 pts) What is the probability that a randomly selected US adult slept more than you did last night?

C.(2 pts) What is the probability that a randomly selected US adult slept less than your friend or family member did last night?

D.(2 pts) Doctors recommend 8 hours of sleep per day for adults to have the health benefits of sleep. What percent of US adults sleeps less than this recommended amount?

E.(2 pts) A colleague at work says that she usually sleeps less than 4 hours each day. Is her sleep amount unusual? Justify your answer by calculating its probability.

F.(2 pts) 10% of US adults sleep more than how many hours?