Probability - Addition Rule

Front

What is the Addition Rule in probability?

Back

The Addition Rule states that the probability of the occurrence of at least one of two events A or B is given by P(A or B) = P(A) + P(B) - P(A and B).

Front

If the probability of event A is 0.3 and the probability of event B is 0.5, what is the probability of A or B if they are mutually exclusive?

Back

P(A or B) = P(A) + P(B) = 0.3 + 0.5 = 0.8.

Front

What does it mean for two events to be mutually exclusive?

Back

Two events are mutually exclusive if they cannot occur at the same time. For example, flipping a coin results in either heads or tails, but not both.

Front

In a pet store, there are 6 puppies, 4 gerbils, and 7 parakeets. What is the total number of pets?

Back

Total pets = 6 (puppies) + 4 (gerbils) + 7 (parakeets) = 17 pets.

Front

What is the probability of choosing a puppy or a parakeet from the pet store?

Back

P(puppy or parakeet) = (Number of puppies + Number of parakeets) / Total pets = (6 + 7) / 17 = 13/17.

Front

What is the probability of a person having a car accident on New Year's Eve if the probability is 0.09?

Back

The probability of having a car accident is 0.09.

Front

What is the probability of a person driving while intoxicated or having a car accident if the probabilities are 0.32 and 0.09 respectively, and the probability of both is 0.15?

Back

P(intoxicated or accident) = P(intoxicated) + P(accident) - P(intoxicated and accident) = 0.32 + 0.09 - 0.15 = 0.26.

Front

If a day of the week is chosen at random, what is the probability of choosing a Monday or Tuesday?

Back

P(Monday or Tuesday) = 2 days / 7 days = 2/7.

Front

What is the probability of rolling a 2 or a 5 on a 6-sided die?

Back

P(2 or 5) = 2 favorable outcomes / 6 total outcomes = 1/3.

Front

What is the probability of a New York teenager owning a skateboard or a bicycle if the probabilities are 0.37 and 0.81 respectively, and the probability of owning both is 0.36?

Back

P(skateboard or bicycle) = P(skateboard) + P(bicycle) - P(both) = 0.37 + 0.81 - 0.36 = 0.82.