A bag contains n white tiles and five black tiles. The tiles are all equal in shape and size. A tile is drawn at random and is replaced. A second tile is then drawn. a Find: i the probability that the first tile is white ii the probability that both the first and second tiles are white. b You are given that the probability of drawing two white tiles is 7/22 , Show that: 3n²-17n-28=0. c Solve the equation, 3n²-17n-28=0 , and hence find the probabilicy that exactly one white and exactly one black tile is drawn.