hi, I am having trouble figuring this problem. I know there are some equations but I do not know which ones they are and how to apply them

Telephone calls arrive at the rate of 18 per hour at the reservation desk for Regional AinNays. a. Find the probability of receiving 3 calls in a 4-minute interval. If required, round your answer to four decimal places. r<s>=— x b. Find the probability of receiving 12 calls in 10 minutes. If required, round your answer to four decimal places. r<12)=i:] c. Suppose that no calls are currently on hold. If the agent takes 5 minutes to complete processing the current call, how many callers do you expect to be waiting by thattime? If required, round your answer to one decimal place. Number of callers = C] What is the probability that no one will be waiting? If required, round your answer to four decimal places. The probability none will be waiting after 5 minutes is C] . d. If no calls are currently being processed, what is the probability that the agent can take 3 minutes for personal time without being interrupted? If required, round youranswer to four decimal places. The probability of no interruptions in 3 minutes is C] .