Abag contains 2 red, 4 yellow, and 6 blue marbles. two marbles are drawn at random. find the portability that both are blue.

Total number of marbles is 12, there are 6 blues.
When picking the first one the probability to pick the right one is 
When we pick the second one there are 11 marbles and only 5 blue so the probabilty is 

We need to pick 2 blues one after another so we multiply probabilities  The probability is around 23%