Lesson Page Uncertainty

Tree diagrams are used to display all possible outcomes of experiments involving more than one event.

Tree diagram: possible outcomes

You need to decide on your snack. You can have white or chocolate milk to drink. To eat you can have chocolate chip or oatmeal cookies. How many different choices do you have?

 Combinations Drinks Cookies Possible Outcomes 2 x 2 4

Example:

 In an experiment, Philip flips two counters. One side of each counter is blue and the other is red. Find all possible outcomes. What is the probability of both counters landing blue side up?
 You can use a tree diagram to show all possible outcomes. Event 1 Event 2 Outcomes Write First Counter Second Counter Blue (B) Blue (B) Blue, Blue (B, B) Red (R) Blue, Red (B, R) Red (R) Blue (B) Red, Blue (R, B) Red (R) Red, Red (R, R) Probability of both blue P (B, B) = 1/4 1favorable outcomes 4 possible outcomes There are 4 possible outcomes. The probability of both counters landing blue side up is 1/4.

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