Answer to Question #296701 in Statistics and Probability for Dayana

Question

1. The average weekly loss of labour hours due to factory accidents is studied on ten labours before and after a new industrial safety awareness program. The 95% confidence interval for the difference in mean of the weekly loss of labour hours before and after the industrial safety awareness program is (2.282, 8.118) in hours. Interpret the confidence interval.
2. A 90% confidence interval for the average salary (in RM) of all CEOs in the electronics industry was constructed using the results of a random survey of 45 CEOs. The interval was (139,048, 154,144). Give a practical interpretation of the interval.

Answer 1

$a)$

The 95% confidence interval of (2.282, 8.118) does not contain the value 0. This shows that the difference in means of the weekly loss of labor hours before and after the industrial safety awareness program is significant.

That is, there exists a significant difference in the population means of weekly loss of labor before and after the industrial safety awareness at 5% level of significance.

$b)$

We are 90% confident that the mean salary of all CEO's in the electronics industry falls in the interval $139048 to $154144.