answers are 18/81, 18/121, 24/88 or 18/99

In a bag, there are 11 marbles. Two marbles are red (R) and nine marbles are blue (B). Draw two marbles, one at a time, with replacement. The tree diagram using frequencies that show all the possible outcomes is as follows: 1st Draw 9B 2R 2nd Draw 9B 2R 9B 2R 81BB 18BR 18RB 4RR Based on the tree diagram, the probability of selecting a red marble on a second try given a blue marble on the first try, P(R[ B), is 18/81 O 18/121