The number of hours medical students work is normally distributed, with a mean of 70 hours and a standard deviation of 10 hours.

(1) Use your standard normal chart to find the z-score associated with the top 1%.

(2) Use the z-formula to find the number of actual hours someone at the top 1% works.

(3) Use your standard normal chart to find the z-score associated with the bottom 10%.

(4) Use the z-formula to find the number of actual hours someone at the bottom 10% works.