The arrival of men at a certain restaurant follows a stationary Poisson process with a rate of 9 men per hour and the arrival of women at the same restaurant also follows a stationary Poisson process with a rate of 6 women per hour. In the next 40 minutes, determine the probability that:

a.) exactly 5 men and 3 women will arrive,

b.) exactly 3 men and 5 women will arrive,

c.) exactly 8 people (men or women) will arrive.