Answer:
a) The null hypothesis is and the alternate hypothesis is
b) A test statistic of -2.06 should be used.
Step-by-step explanation:
Question a:
One water-treatment plant has a target pH of 8.5.
At the null hypothesis, we test if the mean is close to the target. So, the null hypothesis is:
At the alternate hypothesis, we test if it differs from 8.5, so the alternate hypothesis is:
Question b:
The test statistic is:
In which X is the sample mean, is the value tested at the null hypothesis, is the standard deviation and n is the size of the sample.
8.5 is tested at the null hypothesis:
This means that
The mean and standard deviation of 1 hour's test results, based on 17 water samples at this plant, are 8.42 and 0.16, respectively.
This means that
Value of the test statistic:
A test statistic of -2.06 should be used.