You arrive at a bus stop to find there are no busses currently there. Two different lines, line A and line B service the bus stop and both will take you to your destination so you get onto the first bus that arrives. Both busses have arrival times corresponding to exponential distributions and the busses are independent of one another. Bus A on average comes by once every ten minutes. Bus B on average comes by once every 5 mins. What is the probability that you will have to wait more than 8 mins for a bus to arrive