Question

A bag contains 8 blue marbles 5 red marbles and 2 orange marbles , Carolina picks a marble from the bag at random and returns it to the bag and makes a second random selection . What is the probability that two blue marbles were selected

Answer 1

Initial total number of marbles: 8 + 5 + 2 = 15
Initial number of blue marbles: 8

First pick:
p(blue marble) = 8/15

Since the marble from the first pick is returned to the bag, the bag still contains 8 blue marbles and a total of 15 marbles.

Second pick:
p(blue marble) = 8/15

Overall:
p(blue marble followed by blue marble) =
= p(blue marble) * p(blue marble)
= 8/15 * 8/15
= 64/225