Question

Francisco is playing a game with 3 green, 2 yellow, 4 red, and 3 black marbles in a bag. He has calculated the probability of drawing a yellow marble, not replacing it, and then drawing a red marble. Explain the error in his solution. (StartFraction 2 over 12 EndFraction) (StartFraction 4 over 12 EndFraction) = StartFraction 8 over 144 EndFraction

Answer 1

2/12

You take the total number of marbles and you put it under the number of yellow marbles.

Answer 2

The events are dependent, so the sample space changes for the second draw. After drawing the first marble, there are only 11 marbles left. The probability is (

2

12

) (

4

11

) =

8

132

, or

2

33

.

Explanation: