stuck on last homework problem :(

Problem 3: At a call center in Los Angeles County, calls come in at an average rate of six calls per minute. Assume that the wait time from one call to the next follows the exponential distribution. Here we concern only with the rate of calling in and ignore the time spent on the phone. Also, we need to assume that the waiting time between calls is independent. That is, a long delay between two calls doesn't make a shorter waiting period for the next call. (a) What is the average time between two successive calls? (b) What is the probability that exactly ve calls occur within a minute? (c) What is the probability that less than ve calls occur within a minute? (d) After a call is received, what is the probability that the next call occurs in less than 5 seconds? (e) Use rexp function in R to generate 1000 samples with the A you derived from (d), and then draw a EDF plot with ecdf function. Finally, add condence interval to your EDF plot