(4 marks) For the standard normal distribution, nd the value 20 satisfying each of the following conditions. a) PEZD

(4 marks) For the standard normal distribution, find the value zo satisfying each of the following conditions. a) P(-zo < z < b) (4 marks) The lifetime of salmon flies is normally distributed with a mean of 60 days and a standard deviation of 20 days. What percentage of salmon flies live less than 12 days?