Practice 9-1. Probability

Transcription

1 Practice 9-1 Probability You spin a spinner numbered 1 through 10. Each outcome is equally likely. Find the probabilities below as a fraction, decimal, and percent. 1. P(9) 2. P(even) 3. P(number 4. P(multiple of 4) greater than 0) There are eight blue marbles, nine orange marbles, and six yellow marbles in a bag. You draw one marble at random. Find each probability.. P(blue marble) 6. P (yellow marble) 7. What marble could you add or remove so that the probability of drawing a blue marble is 1 3? A box contains 12 slips of paper as shown. Each slip of paper is equally likely to be drawn. Find each probability. 8. P(red) 9. P(blue) 10. P(yellow) 11. P(red or blue) 12. P (red or yellow) 13. P(blue or yellow) 14. P(not red) 1. P (not blue) 16. P(not yellow) You select a letter randomly from a bag containing the letters S, P, I, N, N, E, and R. Find the odds in favor of each outcome. 17. selecting an N 18. selecting an S red blue yellow blue yellow red blue red red red red yellow Practice Course 2 Lesson

2 Practice 9-2 Experimental Probability Suppose you observe the color of socks worn by students in your class: 12 have white, 4 have black, 3 have blue, and 1 has red. Find each experimental probability as a fraction in simplest form. 1. P(white) 2. P(red) 3. P(blue) 4. P(black). P(yellow) 6. P(black or red) Use the data in the table at the right for Exercises Find each experimental probability as a percent. 7. P(fruit) 8. P(granola) 9. P(pretzels) 10. P(carrots) 11. P(not fruit) 12. P(granola or chips) 13. Do an experiment to find the probability that a word chosen randomly in a book is the word the. How many words did you look at to find P(the)? What is P(the)? 14. Suppose the following is the result of tossing a coin times: Solve. heads, tails, heads, tails, heads What is the experimental probability for heads? 1. The probability that a twelve-year-old has a brother or sister is 2%. Suppose you survey 300 twelve-year-olds. About how many do you think will have a brother or sister? 16. a. A quality control inspector found flaws in 13 out of 10 sweaters. Find the probability that a sweater has a flaw. Round to the nearest tenth of a percent. b. Suppose the company produces 00 sweaters a day. How many will not have flaws? c. Suppose the company produces 600 sweaters a day. How many will have flaws? Favorite Snack Survey Results Number of Snack Students Fruit 8 Granola 2 Pretzels 3 Chips 7 Carrots Practice Course 2 Lesson 9-2 2

3 Practice 9-3 Sample Spaces Make a table to show the sample space and find the number of outcomes. Then find the probability. 1. A theater uses a letter to show which row a seat is in, and a number to show the column. If there are eight rows and ten columns, what is the probability that you select a seat at random that is in column 1? Make a tree diagram. Then find the probability. 2. A coin is tossed three times. a. Make a tree diagram that shows all the possible outcomes of how the coin will land. b. Find the probability that the coin will land heads up all three times or tails up all three times. Use the counting principle. 3. A pizza company makes pizza in three different sizes: small, medium, and large. There are four possible toppings: pepperoni, sausage, green pepper, and mushroom. How many different kinds of pizza with one topping are available? 4. You can choose from three types of sandwiches for lunch and three types of juice. How many possible lunch combinations of sandwich and juice can you have? Susan has red, blue, and yellow sweaters. Joanne has green, red, and white sweaters. Diane s sweaters are red, blue, and mauve. Each girl has only one sweater of each color and will pick a sweater to wear at random. Find each probability.. P(each girl chooses a different color) 6. P(each girl chooses the same color) 7. P(two girls choose the same color, 8. P(each girl chooses a red sweater) and the third chooses a different color) Practice Course 2 Lesson

4 Practice 9-4 Compound Events Each letter in the word MASSACHUSETTS is written on a card. The cards are placed in a basket. Find each probability. 1. What is the probability of selecting two 2. What is the probability of selecting two S s if the first card is replaced before S s if the first card is not replaced before selecting the second card? selecting the second card? You roll a fair number cube. Find each probability. 3. P(3, then ) 4. P(2, then 2). P(, then 4, then 6) 6. P(6, then 0) Four girls and eight boys are running for president or vice president of the Student Council. Find each probability. 7. Find the probability that two boys are 8. Find the probability that two girls are elected. elected. 9. Find the probability that the president 10. Find the probability that the president is a boy and the vice president is a girl. is a girl and the vice president is a boy. A box contains ten balls, numbered 1 through 10. Marisha draws a ball. She records its number and then returns it to the bag. Then Penney draws a ball. Find each probability. 11. P(9, then 3) 12. P(even, then odd) P(odd, then 2) 14. P(the sum of the numbers is 2) 1. P(prime, then composite) 16. P(a factor of 8, then a multiple of 2) Practice Course 2 Lesson

5 Practice 9- Simulating Compound Events 1. The table shows the fraction of different types of pencils in Eva s pencil box. a. Design a simulation that can be used to estimate the probability that Eva will need to pick more than 3 randomly chosen glitter pencils from the pencil box before getting a plain pencil. Type Fraction Plain 1 Glitter 2 Message 2 b. Perform 20 trials of the simulation. Then estimate the probability. 2. A grocery store includes one token with every purchase. Half of the tokens are for free merchandise, and the other half are for prizes. a. Design a simulation that can be used to estimate the probability that a customer will need to make at least 2 purchases to receive a token for a prize. b. Perform 20 trials of the simulation. Then estimate the probability. In a satisfaction survey, 11% of a tour guide s customers said that the tour was too short. However, 48% said the tour was great. Estimate the probability that the guide will have to read at least surveys to find one that said the tour was too short. Then estimate the probability that the guide will have to read at least surveys to find one saying the tour was great. 3. Probability of reading at least surveys to find one that said the tour was too short: 4. Probability of reading at least surveys to find one that said the tour was great: Tour Guide Surveys Practice Course 2 Lesson 9-261