Question

A bag contains 4 red marbles, 3 white marbles, and

6 blue marbles. What is the probability of randomly
selecting a red marble, setting it aside, and then
randomly selecting a white marble from the bag?

Answer 1

The probability of the first event is:

P(red marble) = 4/13

After one red marble is set aside, there are 12 marbles left in the bag, including 3 white marbles. The probability of selecting a white marble from those 12 is:

P(white marble after red marble) = 3/12

So the probability of both events happening together (assuming they are independent) is:

P(red and white) = P(red marble) x P(white marble after red marble)

= (4/13) x (3/12)

= 1/13