Maths probability (dependent events and conditional)?

Q1: A box containing 12 gold coins and 10 silver coins. Ann repeats drawing a coin at a time randomly front the box without replacement until a silver coin is drawn. Find the probability that a) exactly two draws are needed b)exactly three draws are needed c) at least three draws are need Q2:65 per cent of... 顯示更多 Q1: A box containing 12 gold coins and 10 silver coins. Ann repeats drawing a coin at a time randomly front the box without replacement until a silver coin is drawn.
Find the probability that
a) exactly two draws are needed
b)exactly three draws are needed
c) at least three draws are need

Q2:65 per cent of staff are single and 40 percent of staff rent flats. 25 per cent of staff are single and rent flats.
One staff is selected randomly from the company.
a) given that the staff member selected is single, Find the probability that he or she rent flat
b) given that the staff member selected rent flat, Find the probability that he or she is single