Question

An experiment involves flipping a coin three times.

The following tree diagram shows the possible outcomes for the experiment.

What is the probability of getting exactly 2 tails?

Enter your answer as a reduced fraction, like this: 3/14

Answer 1

or 2/3

Explanation:

because two flips out of 3 all together is 2/3

Answer 2

Flipping a coin to get H or T is a 50% (0.5) chance respectively
So to get 2 tails we could have gotten:
H T T
T T H
T H T
— P( H T T) = 0.5 x 0.5 x 0.5 = 0.125
— P(T T H) = 0.5 x 0.5 x 0.5 = 0.125
— P(T H T) = 0.5 x 0.5 x 0.5 = 0.125
0.125 + 0.125 + 0.125 = 0.375 = 3/8