Question

A bag contains 4 blue marbles and 7 red marbles. Two marbles are randomly drawn without replacement. Find the probability of the event ""the first marble is red and the second marble is blue""?

Answer 1

8/11

Explanation:

In the given scenario was cannot calculate P(B) directly. As it depends on what happened first, by itself we don’t know what was drawn first. Thus it becomes a conditional probability question:

P( B | A ) ← reads as the probability of “B” happening “given that” “A” has already happened — in this case the probability that the second marble drawn is a blue marble given that the first was a red marble.