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Addition Rule of Probability

HSS-CP.B.7
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Aligned To Common Core Standard:

High School Statistics - HSS-CP.B.7

What is the Addition Rule of Probability? The addition rule of probability represents two formulae; one represents the formula for the non-mutually exclusive events and the other for the mutually exclusive events. In statistical terms, mutually exclusive events are the events that cannot happen at the same time; it represents a situation when one event supersedes the other. The non-mutually exclusive events are the occurrences that can happen at the same time or separately. It represents the sum of the probabilities of two events subtracted from the probability of both events happening together. MUTUALLY EXCLUSIVE EVENTS - The probability of event A or B is equal to the probability of the event A plus the probability of event B P (A or B) = P(A) + P(B) To calculate the probability of the mutually exclusive events, we perform the following steps: 1. Figure out the number of possible events. 2. Calculate the desired outcome. 3. Form ratio for each event. 4. Add the ratios of each event. NON-MUTUALLY EXCLUSIVE EVENTS - The probability of event A or B is equal to the probability of event A plus the probability of event B minus the probability of event A and B P (A or B )= P(A) + P(B) – P(A and B) To calculate the probability of the non-mutually exclusive events, we perform the following steps: 1. Figure out the number of possible outcomes. 2. Calculate the desired outcome. 3. Form the ratio for each event. 4. Add the ratios of each event. 5. Subtract the overlap of both the events. These worksheets and lessons will help students better understand and actively use the Addition Rule of Probability.

Printable Worksheets And Lessons




Homework Sheets

Sorry if you're not a fan of the cute images. My grand daughter insisted.

  • Homework 1 - Lilly is playing cards. What is probability of randomly pulling a diamond or spade out of the deck?
  • Homework 2 - A bag contains 20 lollipops of different color; 7 are yellow, 4 are green, and 9 are red. If a lollipop is selected at random, what is the probability that the lollipop chosen is either yellow or red?
  • Homework 3 - Find the probability that a student picked from this group at random either has hazel or blue eyes?



Practice Worksheets

Coming up with subjects of test surveys is harder than I ever thought it would be.

  • Practice 1 - In a group of 80 people; 15 were regular banana eaters and 42 did not like bananas. Find the probability that a person picked from this group at random is either a regular banana eater or did not like bananas?
  • Practice 2 - In a group of 101 students; 40 are juniors, 50 are female, and 22 are female juniors. Find the probability that a person picked from this group at random is either a junior or female?
  • Practice 3 - In a group of 10 people; 4 have Mercedes and 5 have BMWs. Find the probability that a person picked from this group at random either has BMW or Mercedes?



Math Skill Quizzes

Read these carefully. Many times you will find numbers that just don't matter for your purpose.

  • Quiz 1 - Find the probability of drawing either a king or a spade in a single draw from a pack of 52 playing cards.
  • Quiz 2 - In a group of 60 people; 35 were drinking punch and 23 were eating fish. Find the probability that a person picked from this group at random is either drinking punch or eating fish?
  • Quiz 3 - In a group of 65 people; 32 are drinking tea and 26 are drinking coffee. Find the probability that a person picked from this group at random is either a tea or coffee drinker?