Estimate a Population from a Sample

Look at how much the samples vary, then say how much to trust the estimate.

ExampleLiam takes four random samples of 80 students each at Oakdale Middle School (620 students in all) and counts how many walk to school. The four samples give 41, 37, 44 and 43. What does the spread of these results tell Liam about the estimate?

The samples range from 37 to 44 out of 80
Estimate = about 318 students

Answer: about 318 students

The four counts are close together, so the estimate is fairly stable. Different random samples never give exactly the same answer, so an estimate from one sample should be treated as approximate, not exact.

1.Omar takes four random samples of 60 students each at Oakdale Middle School (620 students in all) and counts how many walk to school. The four samples give 25, 23, 27 and 26. What does the spread of these results tell Omar about the estimate?
Answer: students
2.Jamal takes four random samples of 80 students each at Kingsport Middle School (540 students in all) and counts how many walk to school. The four samples give 33, 32, 35 and 34. What does the spread of these results tell Jamal about the estimate?
Answer: students
3.Omar surveys a random sample of 50 students at Riverton Middle School, which has 480 students in all. In the sample, 11 students walk to school. Estimate how many students in the whole school walk to school.
Answer: students
4.Noah takes four random samples of 60 students each at Kingsport Middle School (540 students in all) and counts how many walk to school. The four samples give 29, 27, 33 and 32. What does the spread of these results tell Noah about the estimate?
Answer: students
5.Maria takes four random samples of 80 students each at Northport Middle School (860 students in all) and counts how many walk to school. The four samples give 36, 33, 40 and 37. What does the spread of these results tell Maria about the estimate?
Answer: students