Page 89 - NUMINO Challenge_D2

10 Probability

Basic Concepts The Number of Outcomes

The number of possible ways an event can occur is called the number of
outcomes.

Ex. Find the number of outcomes that a person can gesture when playing rock-
paper-scissors.

Scissors Rock Paper

Possible outcomes: rock, paper, scissors
Number of outcomes: 3

The probability is the ratio of the number of favorable outcomes to the total

number of outcomes.

Probability Number of favorable outcomes
Total number of outcomes

Example There is a spinner shown on the right. Find the 12
number of outcomes when spinning it. (Exclude
the cases where the pointer lands in between two 53
numbers.) 4

Class Notes

The numbers 1, 2, , , and , are written on the spinner.
Since the five possible outcomes of pointing at a number are , , , ,
and , the number of possible outcomes is .

Try It Again Find the probability of rolling a 3 when a die is rolled.

86 NUMINO Challenge D2