3.45 The time between severe earthquakes at a given region follows a lognormal distribution with a coefficient of varia- tion of 40%. The expected time between severe earthquakes is 80 yr. (a) Determine the parameters of this lognormally distributed re- currence time T. (Ans. 4.308, 0.385) (b) Determine the probability that a severe earthquake will occur within 20 yr from the previous one. (c) Suppose the last severe earthquake in the region took place 100 yr ago. What is the probability that a severe earthquake will occur over the next year?