Question

We wish to give a 95% confidence interval for the difference in average times it takes workers to complete a routine task before and after taking a training class. Below we give the results for two independent samples in which the times (in minutes) were recorded for the task.

		Before Training	After training
	Sample Size	48	44
	Sample Average	9.5	8.6
	Sample SD	2.1	1.9

In what follows let µ₁ denote the population average time of completion without the training and let µ₂ denote the population average time for completion after the training. Give the margin of error for the 95% confidence interval forµ₁ -µ₂.

0.82

1.25

0.69

0.34

0.93

Answer 1

The statistical software output for this problem is :

Margin of error = (1.728 - 0.07) / 2 = 0.82