Question

The health director of a large company is concerned about the effects of stress on the company’s middle-aged male employees. According to the National Center for Health Statistics, the mean systolic blood pressure for males 35 to 44 years of age is 128. The health director examines the medical records of a random sample of 72 male employees in this age group. The Minitab output below displays the results of a significance test and a confidence interval.

1. Do the results of the significance test allow us to conclude that the mean blood pressure for all the company’s middle-aged male employees differs from the national average? Justify your answer.

2. Interpret the 95% confidence interval in context. Explain how the confidence interval leads to the same conclusion as in Question 1.

Short answer

Part (a) Test is not significant.

Part (b) Null hypothesis is rejected.

Step-by-step solution

Part (a) Step 1. Interpretation 

The p-value as indicated in the Minitab output is equal to 0.275 which is greater than 0.05. As a result, the test is not significant and there is insufficient evidence to reject the null hypothesis that there is no difference.

Part (b) Step 1. Interpretation 

The sample mean and test statistic as indicated in the Minitab output is equal to 129.93 and 1.10 respectively. If the sample means is extended to either side of the test statistic at a 95% confidence interval will still belong to the confidence interval. As a result, it shows there is insufficient evidence to reject the null hypothesis that there is no difference.