Odds in Favor and Odds Against

Odds in Favor and Odds Against

Odds compare the number of favorable outcomes to unfavorable outcomes.

1) Identify the counts

• Odds in favor are written as favorable : unfavorable.
• Odds against are written as unfavorable : favorable.

First count how many outcomes support the event and how many do not.

2) Write the ratio

If there are 3 favorable outcomes and 5 unfavorable outcomes:

• odds in favor = 3:5
• odds against = 5:3

3) Simplify if possible

Reduce the ratio the same way you would simplify a fraction, by dividing both parts by the same common factor.

4) Check your answer

Make sure:

• the two parts are in the correct order,
• the numbers come from the counts in the situation,
• the ratio is fully simplified.

Common tip

Do not confuse odds with probability. Probability compares favorable outcomes to all outcomes, while odds compare favorable outcomes to unfavorable outcomes.

When you finish, reread the event and verify that your final answer matches the required form: odds in favor or odds against, simplified.