Voters arrive randomly at a Polling Booth to cast their vote as per a Poisson distributon with an average of 2 voters casting their vote every minute.

(a) (2 points) Find the probability that exactly 3 voters cast their vote in the last minute before the polling booth closes.

(b) (3 points) Find the probability that at least 2 voters cast their vote in the last two minutes before the booth closes.