Lesson 31: Using Sampling to Draw Inferences

Essential Question: What does the data from a random sample tell you about a population?

Word to Know: Variability – a measure of how much the values in a data set vary from each other or from a measure of center (how spread out the data is) More spread out – more variability Closer together – less variability

Problem 1: The data from two random samples of 100 students regarding their lunch preferences are given below. About how many servings of pizza should we order to serve lunch to 1200 students? Student sample Burgers Tacos Pizza Total #1 12 14 74 100 #2 11 77

Problem 2: Given the data in the table below from a random sample of 5000 registered voters, predict the outcome of the election. What percentage of the voters supports the winning candidate? Candidate A Candidate B Candidate C Total 1505 2074 1421 5000

Problem 3: The data from two random samples of 200 students regarding their favorite sports are given below. Make inferences about the data and give the percentage of students who prefer basketball. Student Sample Soccer Football Basketball Track Total #1 40 62 63 35 200 #2 43 64 61 32

Problem 4: Random samples show that about 10 % of the population is left handed. How many pairs of left-handed scissors should we have for classes of about 40 students? What about for 6 students? 76 students?

Problem 5: There are 924 students at a middle school Problem 5: There are 924 students at a middle school. Random samples of students show that about one third attend after-school clubs. How many chairs should be set up for the school-wide Club Day meeting?

Problem 6: The operators of the PlayPlace amusement park want to know how many first-time visitors plan to visit the park again in the next year. They take random samples of 600 first-time visitors as they exit the park asking them: “When do you plan to visit again?” The results are below. In the next year Between 1 and 2 years from now Between 2 and 5 years from now More than 5 years/will not visit again Sample #1 84 128 326 62 Sample #2 76 116 364 44 Sample #3 80 119 345 56 PlayPlace has 720,000 first time visitors each year. Based on these samples above, about how many visitors each year plan to visit the park again in the next year?