There is a bag filled with 4 blue, 3 red and 5 green marbles. A marble is taken at random from the bag, the colour is noted and then it is replaced.
Another marble is taken at random.
What is the probability of getting 2 blues?

1/9

Explanation:

(4 blue + 3 red + 5 green) = 12 total marbles

The probability of getting one blue is 4/12 = 1/3

Since each draw is independent of the last, the probability of two Blue:

Blue = 1/3 * 1/3 = 1/9

Also, 1/9 is the simplified fraction for 16/144