Hw5,6,7. I need help how to solve it

5. Let X = the time in hours between two successive arrivals at the drive-up window of a fast food restaurant. If X has an exponential distribution with 1 = 10, compute the following: (a) The expected time between two successive arrivals. (b) The standard deviation of the time between two arrivals. (c) The median time between the two successive arrivals. (d) The probability that after one arrival it takes at least half an hour before the next arrival? robability And Statistics for Engineers And Scientists, Hayter, A. (2007), Chapter 2 6. Suppose that the time spent online to do homework by a randomly selected student has a gamma distribution with mean 20 minutes and variance 80 minutes. (a) What are the values of a and B? (b) What is the probability that a student spends online at most 24 minutes? (c) What is the probability that a student spends between 20 and 40 minutes online? 7. Suppose Z~N (0,1), find: (a) P(Z