Exhibit 10-3
A statistics teacher wants to see if there is any difference in the abilities of students enrolled in statistics today and those enrolled five years ago. A sample of final examination scores from students enrolled today and from students enrolled five years ago was taken. You are given the following information.
| Today | Five Years Ago |
 | 82.0 | 88 |
σ2 | 112.5 | 54 |
n | 45.0 | 36 |
Refer to Exhibit 10-3. The 95% confidence interval for the difference between the two population means is
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-9.92 to -2.08
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-3.92 to 3.92
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-13.84 to 1.84
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-24.228 to 12.23