Study Guide: Probability and Odds

These web-based activities were developed, during summer sessions from 1997 through 1999, by students at Mainland High School, located in Daytona Beach, FL. As part of Mainland's CCTT grant, the students were given permission by the book's publisher to convert the ancillary materials of the County's adopted Algebra 1 Textbook (Glencoe Algebra 1 - ISBN: 9780028253282) into html format.

The probability of an event is a ratio that tells how likely it is that the event will take place.

Example 1: Mr. Babcock picks 5 of his 25 students in his algebra class at random for a special project. What is the probabilty of being picked?

The probability of being picked is

The probability of any event has a value from 0 to 1. If the probability of an event is 0, it is impossible for the event to occur. An event that is certain to occur has a probabilty of 1. This can be expressed as 0 ≤ P(event) ≤ 1.

Example 2: Find the odds that a member of Mr. Babcock's class will be picked for the special project.

Solve each problem.

1. There are 2 colas, 1 ginger ale, 5 cherry sodas, and 4 rootbeers in the cooler. What is the probabbility of puttling out a cola?

2. It will rain 8 times in November and snow 3 times. The other days it will be sunny. What is the probabilty of a sunny day? the odds of a sunny day?

The odds are 19:11

Use the following information to answer questions #3-6.

At a carnival, there is a bowl of money. It contains 50 quarters, 75 dimes, 100 nickels, and 125 pennies.

3. If one coin is chosen, what is the probabilty that a quarter will be chosen?

4. What would be the odds of choosing a quarter if all of the dimes were removed first?

The odds are 2:9

5. What are the odds that a dime will not be chosen?

The odds are 11:3

6. What are the odds of choosing a penny?

The odds are 5:9