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Chapter 8: Q. 9.20 (page 358)

Worker Fatigue. A study by M. Chen et al. titled "Heat Stress Evaluation and Worker Fatigue in a Steel Plant" (American Industrial Hygiene Association, Vol. 64, pp. 352-359) assessed fatigue in steel plant workers due to heat stress. Among other things, the researchers monitored the heart rates of a random sample of 29 casting workers. A hypothesis test is to be conducted to decide whether the mean post work heart rate of casting workers exceeds the normal resting heart rate of 72 beats per minute (bpm).

Short Answer

Expert verified

Part (a). μis equal to 72bpm.

Part (b). μis greater than 72 bpm.

Part (c). Right tailed test.

Step by step solution

01

Part (a) Step 1. Given information.

To determine whether the average post-work heart rate of casting workers surpasses the usual resting heart rate of 72 beats per minute, a hypothesis test will be undertaken (bpm).

02

Part (a) Step 2. Determine the null hypothesis.  

Let

μ= the mean post-work rate of casting workers.

The mean post-work rate of casting workers is equal to 72 bpm.

The null hypothesis:

So, localid="1651766795538" H0:μ=72bpm

03

Part (b) Step 1. Determine the alternative hypothesis. 

The alternative hypothesis:

Casting employees have a mean post-work rate of more than 72 beats per minute.

So, H0>172bpm

04

Part (c) Step 1. Classify the hypothesis test as two tailed, left tailed, or right tailed. 

This is a right-tailed hypothesis test. This is because the alternative hypothesis test determines that the mean post-work rate of casting workers is more than 72 bpm.

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