The annual series of peak river discharge fits a log-normal distribution. A discharge of 90,OOO cfs has a return period of two years, and a discharge of 600,000 cfs has a return period of 100 years.
Estimate (1) the return period for a discharge of 800,OOO cfs, (2) the discharge associated with a return period of 200 years, and (3) the discharge associated with a return period of 50 years.