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 λ = 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?