Question

A bucket contains 5 blue, 4 green and 5 red balls. Sudheer is asked to pick 2 balls randomly from the bucket without replacement and then one more ball is to be picked. What is the probability he picked 2 green balls and 1 blue ball?

Answer 1

The first pick: the probability of getting green is (# of green balls)/(total # of balls)

The second pick: the first pick is done without replacement, so the # of green balls and total # of balls each decrease by 1. Calculate the # of green balls and total balls left over at this point, then calculate the probability of getting green again.

Third pick: # of blue balls / total # of balls

Remember that the total # of balls has decreased by 1 again after the second pick