Question 6: A chemist is studying the reactions of combining chemicals. She has twelve chemicals for her experiment - 7 acids and 5 bases. Suppose the chemicals are selected at random (i.e., each chemical is equally likely to be chosen). a) In the first round of experimenting, the chemist will choose 3 chemicals to combine. Let W represent the number of acids selected. Assume the chemicals are chosen without replacement. Find the probability that 2 acids are selected for the experiment. b) In the second round of experimenting, the chemist will choose 3 chemicals to combine. Let X represent the number of acids selected in this round. Assume the chemicals are chosen with replacement. Find the probability that 2 acids are selected for the experiment. c) In the third round of experimenting, the chemist will continue to combine chemicals until 3 acids are selected. Let Y represent the number of bases selected for the experiment until the 3"d acid is selected. Assume the chemicals are chosen with replacement. How many total chemicals are expected to be selected until 3 acids are chosen?