The annual maximum rainstorm produces rainfall depths (R) in inches at a site of interest that follow a lognormal distribution with a mean of 4.2 in. and a standard deviation of 1.1 in. (a) Compute the parameters of the lognormal distribution.
(b) Compute the magnitude of the 20-year storm (ie. the 95th percentile).
(c) The drainage system at the site can handle 6 in. of rainfall. Anything beyond that will result in flooding.
Determine the probability that the drainage system will not meet demand for such events.