APFIVE Confidence Interval for Difference in Means
Which of the following is an example of constructing a 95% confidence interval for the difference between the mean number of accidents per month in two departments using independent sample data?
Department Accident Data:
| Department | Mean Accidents | Standard Deviation | Sample Size (n) |
|---|---|---|---|
| First Department | 12.3 | 3.5 | 30 |
| Second Department | 7.6 | 3.4 | 30 |
A
Calculating an interval using a z-interval that ignores the distinct sample sizes.
B
Applying a paired data methodology to the two independent samples.
C
Constructing separate confidence intervals for each department and then subtracting the endpoints.
D
Using the data provided, the 95% confidence interval for the difference (first minus second) is approximately $$ (2.92, 6.48)$$.
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