Costomers arrive at a service window according to a poisson process with parameter = 0.2 per

Question:

Costomers arrive at a service window according to a poisson process with parameter λ = 0.2 per minute.
(a) What is the probability that the time between two successive arrivals is less than 6 minutes?
(b) What is the probability that there will be exactly three arrivals during a given 10-minute period