Event(s) are NOT in the total

CONCEPTS

Equation

• Probability 1 Event Occurs = Number of desired events / Total number of possible events

Tips

• Events not in the total must be removed from the denominator in a probability equation.

PRACTICE PROBLEMS

Question 1 Given: 2 red balls, 3 green balls, 4 yellow balls. All yellow balls are not included, what is the probability a red ball is selected?

-- Answer -- 2/5

2 red balls / (9 total balls - 4 yellow balls) = 2/5

Question 2 Given: 2 red balls, 3 green balls, 4 yellow balls. What is probability a red ball is not selected?

-- Answer -- 7/9

(3 green balls + 4 yellow balls) / 9 total balls = 7/9

ACT PRACTICE PROBLEMS