Question: The lifetime of salmon flies is normally distributed with a mean of 60 days and a standard deviation of 20 days.

a) What percentage of salmon flies lives less than 80 days?

b) What percentage of salmon flies lives between 80 and 101 days?

c) Find the value x such that 6.3% of salmon flies live less than x days.

d) A new diet that is believed to increase the lifespan of the flies is fed to a group of 50 flies. Their average lifetime is 63 days. Find the probability that a group of 50 flies feed on the old diet would have had a lifespan of 63 days or longer.