Question

Cole has a bag of 14 marbles. The bag has 7 red marbles, 4 blue marbles and 3 green marbles. Cole randomly picks a marble, replaces it in the bag, and randomly picks another marble.

What is P (blue, blue)?

Answer 1

P (blue, blue) is 2/14, which simplifies to 1/7.

If only one marble was being picked, the probability would have obviously been 4/14. Since the first picked marble was placed back into the bag and the chances are the same for a second blue one, I think all you have to do is halve the probability to produce 2/14.