Americans receive an average of 19 Christmas cards each year. Suppose the number of Christmas cards is normally distributed with a standard deviation of 5. Let X be the number of Christmas cards received by a randomly selected American. Round all answers to 4 decimal places where possible. Required:

a. If an American is randomly chosen, find the probability that this American will receive no more than 20 Christmas cards this year.

b. If an American is randomly chosen, find the probability that this American will receive between 20 and 24 Christmas cards this year.

c. 73% of all Americans receive at most how many Christmas cards? (Please enter a whole number)