Page 383 - NUMINO_WB_6B

186-P2-1

Pull a Marble Out from a Bag

There are five marbles numbered 1 and seven marbles numbered 2. Pull 3
marbles out without putting the marbles back in the bag. Find the probability
that all 3 marbles pulled out will be numbered 1.

21 2
1
2 1
2 2
2
2
1 1

Step 1. Find the probability that the 1st marble pulled will be numbered 1.

Step 2. Pull the 2nd marble without putting the 1st marble back in the bag. Find the
probability that the 2nd marble pulled will be numbered 1.

Step 3. Pull the 3rd marble without putting the 1st and the 2nd marbles back in the
bag. Find the probability that the 3rd marble pulled will be numbered 1.