EXAMPLE 8.9
Margins of error. In the Rec Sports survey, the margin of error of a 95% confidence interval for any value of and n = 200 is
The results for various values of are
| m | m | ||
|---|---|---|---|
| 0.05 | 0.030 | 0.60 | 0.068 |
| 0.10 | 0.042 | 0.70 | 0.064 |
| 0.20 | 0.056 | 0.80 | 0.056 |
| 0.30 | 0.064 | 0.90 | 0.042 |
| 0.40 | 0.068 | 0.95 | 0.030 |
| 0.50 | 0.070 |
Rec Sports judged these margins of error to be acceptable, and it contacted 225 students, hoping to achieve a sample size of 200 for its survey.