If you draw two marbles in sequence from a bowl with 10 black and 4 yellow marbles and the first marble picked is not replaced, what is the probability that both marbles are yellow ?

Explanation

If the first marble is not returned , the first and second picks are not indepandent . So we most use
the formula ` P(A nnB) = P(A|B) ` . In this case , ` P(Y) = (4)/(14)` as before , but ` P(Y|Y) = (3)/(13)`
bacause there are only 13 marbles left , of which only 3 are yellow . Therefore .
` P(YnnY)= P(Y)P(Y |Y)= ((4)/(14))((3)/(13)) = (12)/(182) = (6)/(91)`