A restaurant receives 9 cartons of milk daily. On a random day, the number of cartons with a defective screw cap among them is equal to 2. One of the employees picks up 4 cartons.

a) What is the probability that the employee receives exactly 1 milk cartons with the defect?

b) What is the probability that the employee receives more than 3 milk carton with the defect?

c) What is the probability that the employee receives exactly 1 defective milk cartons if the employee receives 3 or fewer milk cartons with the defect?

d) What is the expected number of cartons with the defect?

e) Calculate the variance of the number of defective milk cartons.