Unit 5 Probability-­‐ Experimental Probability Identify the sample space and the outcome shown for each experiment 1. tossing two coins 2. spinning a spinner 3. selecting a marble 10 marble
s (hh, ht, th, tt) (RGB) Write impossible, unlikely, as likely as not, likely, or certain to describe each event. 4. Marlo purchased a new pair of shoes. She takes one shoe out of the box. The shoe is for the left foot.-­‐ as likely as not 5. Sam takes the bus to school. The bus came late twice in the last two weeks. The bus will be late today. -­‐ unlikely 6. Tammy dropped two quarters on the floor. At least one of them lands heads up.-­‐ likely An experiment consists of randomly choosing a marble from a Outcome Frequency bag. Use the results in the table to find the experimental Red 4 probability of each event. Blue 6 Green 6 7. choosing a yellow marble 9/25 Yellow 9 8. choosing a blue marble 6/25 9. not choosing a green marble 19/25 10. Sports -­‐A ski lodge inspects 80 skis and finds 4 to be defective. a. What is the experimental probability that a ski chosen at random will be defective? 1/20 or 5% b. The lodge has 420 skis. Predict the number of skis that are likely to be defective. 21 11. The table shows the results of a survey asking students the season of their birthday. What is the experimental probability that a student has a birthday during the summer? Season Birthdays Fall 39 51 Winter 27 130 Spring 13 Summer 51 12. You and your friend can either go swimming or to a movie on Thursday. The weather forecast says there is a 70% chance of rain on Thursday. Should you plan on going swimming or to a movie? Explain. 13. Critical Thinking -­‐ Tell why it is important to repeat an experiment many times. 14. Write About It -­‐Explain what it means for an event to have a 50-­‐50 chance of happening. 15. How many outcomes are in the sample space for an experiment consisting of rolling two standard number cubes? 36 16. Estimation-­‐A manufacturing company produced 986 units in one day. Of those, 9 units were found to be defective. Estimate the experimental probability that a unit produced that day was defective. Then predict approximately how many units will be defective when 5680 units are produced in one week. .1% -­‐-­‐-­‐-­‐ approximately 57 unites Challenge A coin is tossed 3 times. Use the sample space for this experiment to describe each event below as impossible, unlikely, as likely as not, likely, or certain. Justify each answer. 17. At least 2 heads 18. 2 heads and 1 tail as likely as not (50%) 37.5% unlikely 19. 2 tails and 1 head 20. 3 tails 37.5% unlikely 12.5% unlikely 21. One coin is tossed 20 times. a. The experimental probability of the coin showing heads is 65%. How many times did the coin show tails? The coin landed tails up 35% of the time. .35 * 20 = 7 times b. If the coin is tossed ten more times, how many more times must the coin land showing tails for the experimental probability of tails to be 50%? If the coin was tossed ten more times, this would bring the total trials up to 30. In order to be 50%, a total of 15 times landing on heads needs to occur. Since the coin has already landed on tails 7 times, it would need to land 8 more times