1. Lesson 31: Using Sampling to Draw Inferences

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

3. 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

4. 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

5. Problem 2: Given the data in the table below from a random sample of 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

6. 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

7. 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?

8. 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?

9. 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?