Question

There are 10 red and 20 yellow balls. Drawing 3 balls without replacement, what is the chance the first is red and the next two are yellow?

Answer 1

10 + 20 = 30 total balls.

Picking red = 10/30 = 1/3

After picking one ball there are 29 balls left.

Picking a yellow next is 20/29

Then there are 28 balls left and 19 yellow left, so picking another yellow would be 19/28

The probability of picking red first then two yellow = 1/3 x 20/29 x 19/28 = 95/609