135 UB students were surveyed and asked how many hours a week they spent studying. The results are in the table below.



Less than 5
5 to 10
More than 10
Total
Male (M)
25
25
20
70
Female (F)
20
30
15
65
Total
45
55
35
135
a) Complete the joint and marginal probability. (4 marks)

b) Find the probability that a student studied 5 to 10 hours. (2 marks)