The annual series of peak flow rates for a river is found to fit a log-normal distribution. A discharge of 22 m'ls has a return period of 1. I years, and a discharge of 200 m'/s has a return period of 35 years.
Determine (1) the discharge with a return period of 100 years, (2) the return period for a discharge of 250 m'ls, and (3) the probability that a flow rate of 250 m3/s will be equaled or exceeded in the next 50 years.