A hire company has two electric lawnmowers which it hires out by the day. The number of demands per day for a lawnmower has the form of a Poisson distribution with mean 1.50. In a period of 100 working days, how many times do you expect

(a) neither of the lawnmowers to be used,

(b) some requests for the lawnmowers to have to be refused? If each lawnmower is to be used an equal amount, on how many days in a period of 100 working days would you expect a particular lawnmower not to be in use? (MEI)