If the average survival time of a red blood cell in the human body is 120 days with a standard deviation of 8 days, what percentage of the cells will survive for each of the following events: (using a normal distribution)

a) BETWEEN 112 AND 128 DAYS

b) more than 128 days

c) less than 112 days

d) at least 115 days

e) less than 108 days

Thank you.