Probability

Warm-Up Kate has a recipe that needs 3 4 tsp. of butter for every 2 cups of milk. If Kate increases the amount of milk to 4 cups, how many tsp. of butter are needed? 6 8 𝑡𝑠𝑝 1 1 2 𝑡𝑠𝑝 3 8 𝑡𝑠𝑝 1 1 3 𝑡𝑠𝑝

Probability

What is Probability? Probability is the likelihood something will happen. It can either be written as a fraction or as a percent. In order to solve probability, just create your fraction and multiply. For example: what are the odds of flipping a coin and it landing on heads? 1 ℎ𝑒𝑎𝑑 2 𝑐ℎ𝑜𝑖𝑐𝑒𝑠 What are the odds of flipping a coin twice and each time it landing on heads? 1 2 x 1 2 = 1 4

Independent Probability Independent Probability: each probability does not depend on other events. In independent probability, your denominator should stay the same. For example, having children…the gender of the first child does not determine the gender of the second child. So, what are the odds of having one boy then one girl? 1 2 x 1 2 = 1 4

Dependent Probability Dependent Probability: each probability does depend on other events. In dependent probability, your denominator should change. For example, there is a bag with 5 green marbles, 2 blue marbles, and 3 yellow marbles. What is the probability of first choosing 1 green marble, then, without replacing it, choosing 1 yellow marble? 1 2 𝑥 1 3 = 1 6

Practice What is the probability of choosing a boy in this class? What is the probability of choosing a girl in this class? What is the probability of choosing someone from the red group? yellow group? blue group? green group? purple group? What is the probability of choosing a boy in the class, having him leave, then choosing a girl? What is the probability of choosing a girl in the class, having her leave, then choosing a girl? What is the probability of choosing a boy in the class, having him leave, then choosing a boy?