Our national lotto draws, each week, 5 numbers from the set of 36 numbers, and we permanently mark these 5 numbers in our map. The winner in our competition will be the person who firstly has his 3 numbers marked.
What is the probability that our competition:
a) ends in the first week?
b) ends in the second week?
c) ends in the third week?
And the most important:
d) What is the expected number of weeks for us to have a winner?