1. a bag contains 12 red checkers and 6 black checkers. you will randomly select two checkers, one at a time, without replacement. (a) fill in the probabilities on each branch of the tree diagram below. write the probabilities as fractions in simplified form. (b) in how many ways can you select two checkers so that at least one of the checkers is red? list the ways. (c) what is the probability that you select a black checker and then a red checker? show your work.