Assumes that jobs arrive every 20 seconds on average. Let X be the waiting time (in minute) until a job arrives. Please find the probability of waiting less than or equal to 30 seconds, i.e., 0.5 minute to get a job, i.e., Pr(X 0.5). (Hint: First, as the waiting time, X has exponential distribution. Then find the rate parameter , which is the average number of jobs arriving within one minute.)