Question

a bag contains 12 marbles of which 4 are red and 8 are blue. if two marbles are drawn at random, what is the probability that both are red?

Answer 1

`(1)/(11)`

Explanation:

`(4)/(12) * (3)/(11) = (1)/(3) * (3)/(11) = (1)/(11)`

We start with 12 marbles. So the probability of selecting a red marble is 4/12, or 1/3. Since this marble is not returned, we now have 11 marbles left, so the probability of selecting a second red marble is 3/11. Multiply 1/3 by 3/11, obtaining 1/11.