Question

A bag contains 10 marbles: 2 are green, 6 are red and 2 are blue. Chau choose a marble at random, and without putting it back chooses another at random. What is the probability that both marbles he chooses are green.

Answer 1

The answer is 2/90

Multiply 2/10 by 1/9

This is because the first time there are 2 green marbles and ten marbles total but the second time he had already taken out a green marble so there is only 1 green marble left and 9 marbles total.
Hope this helps :)