Tree Diagrams Probability Worksheet With Answer Key (Page 4 of 5) in pdf

Tree Diagrams Probability Worksheet With Answer Key Page 4

Draw the first level of the tree diagram

This tree diagram shows the possible outcomes after 1 flip of the coin. Remember that we can have up to 3

flips, so the diagram is not complete yet. If the coin comes up heads, we flip the coin again. If the coin comes

up tails, we stop.

Draw the second and third level of the tree diagram

In this tree diagram you can see that we add up the points we get with each coin flip. After three coin flips, the

game is over.

Find the relevant outcomes and compute the probability

We are interested in getting exactly 3 points during the game. To find these outcomes we look only at the tips of

the tree. We end with exactly 3 points when the coin flips are

(H; T) with probability 1/2 ×1/2 =1/4;



(H; H; H) with probability 1/2 × 1/2 × 1/2 =1/8.

Notice that we compute the probability of an outcome by multiplying all the probabilities along the path from

the start of the tree to the tip where the outcome is. We add the above two probabilities to obtain the final

probability of getting exactly 3 points as 1/4 + 18 = 3/8.

Tree Diagrams Probability Worksheet With Answer Key Page 4