Question

A bag contains 10 marbles: 4are green, 2are red, and 4 are blue. Carmen chooses a marble at random, and without putting it back, chooses another one at random. What is the probability that both marbles she chooses are blue?

Answer 1

`|\Omega|=10\cdot9=90\\|A|=4\cdot3=12\\\\P(A)=(12)/(90)=(2)/(15)`

Answer 2

2/15

Explanation:

There is a 4/10 probability that she chooses blue the first time, but the second time it is a 3/9 chance because she didn't put the marble back so there are 9 marbles in total, 3 blue ones.

4/10 x 3/9 = 2/5 x 1/3 = 2/15

I hope this helps :)

Edit: Messed up the multiplication, whoops!