There are 5 white mice, 6 brown mice, and 7 gray mice in a cage. For your

Question:

There are 5 white mice, 6 brown mice, and 7 gray mice in a cage. For your psychology experiment, you reach in and randomly select 3 to run in a maze.
a. What is the expected and standard deviation in the number of white mice which are selected?
b. What is the probability that at least 2 of the mice selected are white?
c. What if you had 5000 white mice, 6000 brown mice, and 7000 gray mice to choose from? You still need 3 mice to run in the maze. What is the approximate probability that at least 2 of the mice selected are white?