At a local coffee shop, on average, 6 customers get served every 10-minute interval during 12-1pm (lunch time).

a) Calculate the probability that exactly 30 customersget served during 12-1pm.

b) Calculate the probability that atleast 30 customersget served during 12-1pm.

c) Calculate the probability thatbetween 10 and 30 (10<= n <= 30) customersget served during 12-1pm.

d) Calculate and plot the PMF for the first 20 customers.