Math7 Name _________________________________ (13.1) Introduction to Probability What is Probability? ___________ _________ _ Theoretical Probability What is it? How is it calculated? Examples: 1) A bag contains 4 cherry, 6 lemon, 3 strawberry, and 2 orange Starbursts. Find each probability. Write each answer as a fraction and a percent. a) P(orange) = b) P(strawberry) = c) P(lemon) = d) P(not cherry) = 2) You roll a 30-­‐sided number cube. Find each probability. Write each answer as a fraction and a percent. a) P(roll 25) = b) P(multiple of 4) = c) P(prime #) = Practice: Experimental Probability What is it? How is it calculated? Example: You have a container with 2 yellow, 3 blue, and 5 red cubes. Perform 20 trials in which you choose one cube without looking. Tally your results in the table. Then record each experimental probability. Yellow Blue Red P(yellow) = P(red) = P(blue) = Math7 (13.1) Notes Name _________________________________________ Using Theoretical Probability 1) Pointer lands on green 2) Pointer lands on 7 3) Pointer lands on an even number 4) Pointer lands on a prime number 5) You have a spinner with the numbers 1,2,3 equally spaced on it. a) If you spin the spinner once, what is the probability it will land on 2? b) If you spin it 42 times, how many times would you expect it to land on 2? 6) In a bag, there are 5 red, 3 orange, 1 white, and 6 green jellybeans. a) If you choose one jelly bean without looking, what is the probability that it is green? b) If the bag contained 60 jelly beans, how many would you expect to be green? c) How many jellybeans would you expect to pick before you would select 9 orange jellybeans? 7) According to the A.C. Nielsen Co., 66% of U.S. households have 3 or more televisions. If a 2,500 households were surveyed, how many would you expect to have 3 or more televisions? 8) Tom has a 0.375 batting average in his baseball league. a) In the next game, he bats 5 times. About how many hits would you expect him to get? b) If over the next 10 games he bats 40 times, about how many hits do you expect him to get? Practice: 1) What is the probability that the spinner used in problems 1-­‐4, lands on a number that is a multiple of 4? 2) If you spin the spinner 40 times, how many times would you expect it to land on a multiple of 4?