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
53
20-29 61
30-39 67
40-49 51
50-59 72
≥
60
100

One customer is chosen at random for a prize giveaway. (Round answers to 4 decimal places.)

a. What is the probability that the customer is at least 40 but no older than 59?

b. What is the probability that the customer is either older than 60 or younger than 20?

c. What is the probability that the customer is at least 60?