"Ryanair charges a mean base fare of $59. In addition, the airline charges for checking in at the airport, carry-on baggage, checked baggage, and inflight food/beverage. These additional charges average $39 per passenger. Suppose a random sample of 60 passengers is taken to determine the total cost of their flight on Ryanair. The population standard deviation of total flight cost is known to be $25."

a. What is the probability the sample mean will be within $10 of the population mean cost per flight?
b. What is the probability the sample mean will be within $5 of the population mean cost per flight?
c. What is the probability the sample mean will exceed $100?