Question

A bag contains 8 black marbles, 5 white marbles and 12 red marbles. What is the probability of selecting a red marble, not replacing it, then selecting a white marble?

Answer 1

Explanation:

Total balls = 12 + 5 + 8 = 25 marbles

Probability of getting white marbles = 5/24

Probability of red marbles = 12/24 = 1/2

Now

Probability = 1/2 × 5/24 + 1

Probability = 1/2 × 5/25

Probability = 5/50

Probability = ⅒

Answer 2

1/10

Explanation:

8 black marbles, 5 white marbles and 12 red marbles = 25 marbles

P(red) = red/total = 12/25

Remove the marble

8 black marbles, 5 white marbles and 11 red marbles = 24 marbles

P(white) = white/total = 5/24

P(red, remove,white) = 12/25 * 5/24

=12/24 * 5/25

=1/2 * 1/5

=1/10