In: Statistics and Probability
A bowl of fruit contains 5 bananas, 6 oranges, and 3 apples. Two fruits are selected one after another without replacement. What is the probability that the second fruit drawn is an apple given the first fruit drawn was a banana?
My answer is (ba)+(oa)+(aa) / (bb) + (bo) + (ba) which is wrong.. why?
P(A | B) = P(A and B) / P(B)
P(second fruit is an apple | first fruit is banana) = P(first fruit is banana and second fruit is an apple) / P(first fruit is banana)
= ((ba)) / ((bb) + (bo) + (ba))
= (5/14 * 3/13) / [(5/14 * 4/13) + (5/14 * 6/13) + (5/14 * 3/13)]
= (15/182) / (65/182)
= 15/65
= 3/13