3. A clinic has two operation rooms. The service times are assumed to be independent, exponentially distributed with mean 15 minutes. Aye arives when both operation rooms are empty. Bar amives 10 minutes later while Aye is still under surgery. Another 20 minutes later Can arrives and both Aye and Ban are still under surgery. No other patient arrives during this 30-mimute interval. a-) What is the probability that Aye will be ready before Bar? b-) What is the probability that Can will be ready before Aye? c-) What is the probability that Can will be ready before Ban? d-) Detemine the distribution function of the waiting time in the system for Can. Find the mean and variance.