The weights of ice cream cartons are normally distributed with a mean weight of 7 ounces and a standard deviation of 0.3 ounces.
(a) What is the probability that a randomly selected carton has a weight greater than 7.11 ounces?
(b) A sample of 25 cartons is randomly selected. What is the probability that their mean weight is greater than 7.11 ounces?