Consider the vending machines on campus. There are three different types: snack dispensers,
hot drink dispensers, cold drink dispensers. Of the vending machines, 25% sell snacks, 35%
sell hot drinks and 40% sell cold drinks. Suppose that servicing is needed by 1/2 the snack
machines, 1/5 the hot drink machines and 1/3 the cold drink machines. What is the probability that a machine chosen at random needs servicing?
