A garage has three vans which can be hired out for a day at a time. The total number of requests for the hire of a van, for any particular day, has a Poisson distribution with mean 2. If, for any day, fewer than three requests are received for the hire of a van for that day, the vans used are chosen at random. Find the probability that a particular van is not used on a given day.
Answer: 0.406
Solution 
