Please find the calculation formula for the life expectancy.

It's a modeling and simulation work.

Roy is now concerned with his analysis on the assumption that his client will live until age 90. After all, she is healthy and might live many years beyond 90, or she could be in a car accident and die at age 62. To account for this uncertainty in the clients age at death, Roy would like to model his clients remaining life expectancy as a random variable between 0 and 45 years

that follows the lognormal distribution with a mean of 20 and a standard deviation of 10 (rounded to the nearest integer). Under this assumption, what is the maximum amount that Roy should advise his client to withdraw on her 60th birthday that limits the chance that she will run out of money before her death to a maximum of 2%? How much should the client expect to leave to her heirs?