red_pe_ch_10.pdf

# 10 predict the number of students in a school who

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10. Predict the number of students in a school who like gym class. Sample A A random sample of 8 students from the yearbook Sample B A random sample of 80 students from the yearbook 11. pter 10 Probabilit and Statistics Predict the number of defective pencils produced per day. Sample A A random sample of 500 pencils from 20 machines Sample B A random sample of 500 pencils from 1 machine 9 +(-6)=3 3 +(-3)= 4 +(-9)= 9 +(-1)= 1. VOCABULARY Why would you survey a sample instead of a population? 2. CRITICAL THINKING What should you consider when conducting a survey? 1 2 Help with Homework

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Section 10.6 Samples and Populations 445 Write and solve a proportion to answer the question. (Section 6.3) 20. What percent of 60 is 18? 21. 70% of what number is 98? 22. 30 is 15% of what number? 23. What number is 0.6% of 500? 24. MULTIPLE CHOICE What is the volume of the pyramid? (Section 9.5) A 40 cm 3 B 50 cm 3 C 100 cm 3 D 120 cm 3 12. FOOD You ask 125 randomly chosen students to name their favorite food. There are 1500 students in the school. Predict the number of students in the school whose favorite food is pizza. Determine whether you would survey the population or a sample. Explain. 13. You want to know the average height of seventh graders in the United States. 14. You want to know the favorite types of music of students in your homeroom. 15. You want to know the number of students in your state who have summer jobs. 16. THEATER You survey 72 randomly chosen students about whether they are going to attend the school play. Twelve say yes. Predict the number of students who attend the school. 17. CRITICAL THINKING Explain why 200 people with email addresses may not be a random sample. When might it be a random sample? 18. LOGIC A person surveys residents of a town to determine whether a skateboarding ban should be overturned. a. Describe how the person could conduct the survey so that the sample is biased toward overturning the ban. b. Describe how the person could conduct the survey so that the sample is biased toward keeping the ban. 19. A guidance counselor surveys a random sample of 60 out of 900 high school students. Using the survey results, the counselor predicts that approximately 720 students plan to attend college. Do you agree with her prediction? Explain. 3 Favorite Food Pizza 58 Hamburger 36 Pasta 14 Other 17 Maybe 5% Do you plan to attend college? Yes 75% No 20% Survey Results Theater Ticket Sales Adults Students 522 210 4 cm 6 cm 5 cm
446 Chapter 10 Probability and Statistics Lesson Tutorials You have already used unbiased samples to make inferences about a population. In some cases, making an inference about a population from only one sample is not as precise as using multiple samples. 1. PACKING PEANUTS Work with a partner. Mark 24 packing peanuts with either a red or a black marker. Put the peanuts into a paper bag. Trade bags with other students in the class. a. Generate a sample by choosing a peanut from your bag six times, replacing the peanut each time. Record the number of times you choose each color. Repeat this process to generate four more samples. Organize the results in a table.

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