Posted by **Alejandra** on Sunday, October 24, 2010 at 7:41pm.

The caffeine content of a cup of home-brewed coffee is a normally distributed random variable with a mean of 115 mg with a standard deviation of 20 mg.

(a) What is the probability that a randomly chosen cup of home-brewed coffee will have more than 130 mg of caffeine?

(b) Less than 100 mg?

(c) A very strong cup of tea has a caffeine content of 91 mg. What is the probability that a cup of coffee will have less caffeine than a very strong cup of tea?