A store manager gathers some demographic information from the store's customers. The following chart summarizes the age-related information they collected: AGE Number of Customers
< 20 57
20 - 30 51
30 - 40 79
40 - 50 96
50 - 60 99
Greater than or equal to 60 65
Total customers is 447

Required:
a. What is the probability that the customer is at least 20 but no older than 40?
b. What is the probability that the customer is either older than 50 or younger than 30?
c. What is the probability that the customer is at least 50?