The weights of ice cream cartons are normally distributed with a mean weight of 7 ounces and a standard deviation of 0.4 ounce. (a) What is the probability that a randomly selected carton has a weight greater than 7.15 ounces? (b) A sample of 36 cartons is randomly selected. What is the probability that their mean weight is greater than 7.15 ounces? (a) The probability is (Round to four decimal places as needed.)