Arrivals to a an automated teller machine atm are distributed according to a Poisson distribution with a mean equal to three per 15 minutes ...

  

1)Arrivals to a an automated teller machine atm are distributed according to a Poisson distribution with a mean equal to three per 15 minutes.
a) Determine the probability that in a given 15 minutes segment no customers will arrive at the atm.
b) What is the probability that fewer than four customers will arrive in a 30 minute segment?

2)A population of 10 items contains 3 that are red and 7 that are green. What is the probability that in a random sample of 3 items without replacement, 2 red and 1 green items are selected?