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Clarifications: Each clarification provides an explanation of the indicator/objective to help teachers better understand the concept. Classroom examples are often included to further illustrate the concept. While classroom examples could be shared with the students, the intended audience for the explanation/clarification is the classroom teacher-not the student. In addition, classroom examples may or may not reflect the assessment limits.

Standard 5.0 Knowledge of Probability

Topic B. Theoretical Probability

Indicator 1. Determine the probability of one simple event comprised of equally likely outcomes

Objective b. Express the probability of an event as a decimal

Assessment limit: Use a sample space of 10, 20, 25, or 50 outcomes

Clarification

Probability is the chance or likelihood of an event happening. Theoretical probability is the probability of an event occurring based on mathematical counting techniques. The outcomes are all the possible results of an activity that can occur. When rolling a number cube there are 6 possible numbers that can come up. There are 6 outcomes for rolling a number cube. An event is a specific set of outcomes, known as favorable outcomes, from the activity. When rolling a number cube there are 3 ways to roll an even number. Rolling an even number with a number cube is an event. An event composed of one single event is called a simple event.

Classroom Example 1

Marla has a box of chocolate-covered candies. Of the 20 pieces of candy in the box, 5 have caramel centers, 7 have fudge centers, and 3 have cherry centers. Maria picks one piece of candy without looking. What is the probability that it has a fudge center? Express your answer as a decimal.

Answer:

P(event) = equation image

Since there are 20 different candies, there are 20 possible outcomes. Since there are 7 with fudge centers, there are 7 favorable outcomes. Therefore, the probability is:

P(fudge center) = 7/20

Since the question asks for the answer in decimal form the student must rewrite the fraction as a decimal:

7/20 = 0.35

Classroom Example 2

The spinner below is divided into 10 equal sized sections.

spinner image

What is the probability of spinning and landing on a red section? Express your answer as a percent.

Answer:

P(event) = equation image

Since there are 10 different sections, there are 10 possible outcomes. Since there are 4 sections that are red, there are 4 favorable outcomes. Therefore, the probability is:

P(red) = 4/10

Since the question asks for the answer as a percent, the student must rewrite the fraction as a percent:

4/10 = 40%
/instruction/clarification/mathematics/grade6/xml/5B1b.xml
Resources for Objective 5.B.1.b:
CLARIFICATIONS | Sample Assessments |