Answer:
1.
The null hypothesis is ![H_0: \mu = 4](https://tex.z-dn.net/?f=H_0%3A%20%5Cmu%20%3D%204)
The alternate hypothesis is ![H_1: \mu > 4](https://tex.z-dn.net/?f=H_1%3A%20%5Cmu%20%3E%204)
2.
The p-value of the test is of 0.0045.
3.
The p-value of the test is low(< 0.01), which means that there is enough evidence that the flow rate is more than 4 gallons per minute (gpm) and thus, the pump should be put into service.
Step-by-step explanation:
A new centrifugal pump is being considered for an application involving the pumping of ammonia. The specification is that the flow rate be more than 4 gallons per minute (gpm).
At the null hypothesis, we test that the mean is 4, so:
![H_0: \mu = 4](https://tex.z-dn.net/?f=H_0%3A%20%5Cmu%20%3D%204)
At the alternate hypothesis, we test that the mean is more than 4, that is:
![H_1: \mu > 4](https://tex.z-dn.net/?f=H_1%3A%20%5Cmu%20%3E%204)
The test statistic is:
![t = \frac{X - \mu}{\frac{s}{\sqrt{n}}}](https://tex.z-dn.net/?f=t%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Cfrac%7Bs%7D%7B%5Csqrt%7Bn%7D%7D%7D)
In which X is the sample mean,
is the value tested at the null hypothesis, s is the standard deviation and n is the size of the sample.
4 is tested at the null hypothesis:
This means that ![\mu = 4](https://tex.z-dn.net/?f=%5Cmu%20%3D%204)
In an initial study, eight runs were made. The average flow rate was 6.4 gpm and the standard deviation was 1.9 gpm.
This means that ![n = 8, X = 6.4, s = 1.9](https://tex.z-dn.net/?f=n%20%3D%208%2C%20X%20%3D%206.4%2C%20s%20%3D%201.9)
Test statistic:
![t = \frac{X - \mu}{\frac{s}{\sqrt{n}}}](https://tex.z-dn.net/?f=t%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Cfrac%7Bs%7D%7B%5Csqrt%7Bn%7D%7D%7D)
![t = \frac{6.4 - 4}{\frac{1.9}{\sqrt{8}}}](https://tex.z-dn.net/?f=t%20%3D%20%5Cfrac%7B6.4%20-%204%7D%7B%5Cfrac%7B1.9%7D%7B%5Csqrt%7B8%7D%7D%7D)
![t = 3.57](https://tex.z-dn.net/?f=t%20%3D%203.57)
P-value of the test:
The p-value of the test is the probability of finding a sample mean above 6.4, which is a right-tailed test with t = 3.57 and 8 - 1 = 7 degrees of freedom.
With the help of a calculator, the p-value of the test is of 0.0045.
3. Should the pump be put into service?
The p-value of the test is low(< 0.01), which means that there is enough evidence that the flow rate is more than 4 gallons per minute (gpm) and thus, the pump should be put into service.