Question: The results of a national survey showed that on average, adults sleep 6.9 hours per night. Suppose that the standard deviation is 1.2 hours and that the number of hours of sleep follows a bell-shaped distribution.
a. Use the empirical rule to calculate the percentage of individuals who sleep between 4.5 and 9.3 hours per day.
b. What is the z-value for an adult who sleeps 8 hours per night?
c. What is the z-value for an adult who sleeps 6 hours per night?