There are two types of vehicle (passenger car and truck) that cross a bridge site. The truckto-car ratio that crosses the bridge is 4. The average number of cars that cross a particular one-lane bridge is 4.3 per hour. Assume that the arrival rate of cars any time within a day is the same (i.e., the average number of cars crosses the bridge site is the same during the daytime and nighttime).

(a) What is the probability that ten cars are observed before one truck crosses the bridge. P = _______

(b) What is the probability of more than one vehicle (i.e. either car or truck) crosses the bridge in one hour? P = ________

(c) If a truck just crossed the bridge, what is the probability that no truck will cross the bridge in the next one hour? P = _______

(d) What is the waiting time that will have a 90% chance of seeing at least one car passes the bridge? P = _________