Question

Geoff has a bag that contains 4 red marbles and 6 blue marbles. He chooses two marbles at random and does not replace them. What is the probability that the first marble is blue and the second marble is red? A. B. C. D.

Answer 1

Total number of marbles = 10

Number of red marbles = 4

Number of blue marbles = 6

Probability = $\frac{number of favorable outcomes}{total number of outcomes}$

The probability that the first marble is blue = $\frac{6}{10}$

The probability that the first marble is red = $\frac{4}{9}$ ; 9 because 1 marble has already been taken out.

Joint probability= probability of event A * Probability of event B

= $\frac{6}{10}\times\frac{4}{9}$=$\frac{24}{90}= \frac{4}{15}$