Question

A bag contains 3 red marbles, 4 blue marbles, and 5 white marbles. What is the probability of NOT pulling out a red marble three times if none are replaced?
A.35/288
B.21/55
C.6/11
D.210/1728

Answer 1

I just do not know how to do this.... Having much difficulty

Answer 2

There are 12 marbles in the container, 9 of which are not red.
On the first draw, the probability of drawing a non red = 9/12
On the second draw, the probability of drawing a non red = 8/11
On the third draw, the probability of drawing a non red = 7/10
The probability of not drawing a red marble on the first three draws is:
9/12 * 8/11 * 7/10 = 504/1320 which simplifies to 21/55.