Answer:
i:
The appropriate null hypothesis is ![H_0: p \geq 0.2](https://tex.z-dn.net/?f=H_0%3A%20p%20%5Cgeq%200.2)
The appropriate alternative hypothesis is ![H_1: p < 0.2](https://tex.z-dn.net/?f=H_1%3A%20p%20%3C%200.2)
The p-value of the test is 0.1057 > 0.05, which means that there is not sufficient evidence that fewer than 20% of the museum visitors make use of the device, and so, it should not be withdrawn.
ii:
The p-value of the test is 0.1057
Step-by-step explanation:
Question i:
The device will be withdrawn if fewer than 20% of all of the museum’s visitors make use of it.
At the null hypothesis, we test if the proportion is of at least 20%, that is:
![H_0: p \geq 0.2](https://tex.z-dn.net/?f=H_0%3A%20p%20%5Cgeq%200.2)
At the alternative hypothesis, we test if the proportion is less than 20%, that is:
![H_1: p < 0.2](https://tex.z-dn.net/?f=H_1%3A%20p%20%3C%200.2)
The test statistic is:
![z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}](https://tex.z-dn.net/?f=z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Cfrac%7B%5Csigma%7D%7B%5Csqrt%7Bn%7D%7D%7D)
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.
0.2 is tested at the null hypothesis:
This means that
.
The device will be withdrawn if fewer than 20% of all of the museum’s visitors make use of it. Of a random sample of 100 visitors, 15 chose to use the device.
This means that ![n = 100, X = \frac{15}{100} = 0.15](https://tex.z-dn.net/?f=n%20%3D%20100%2C%20X%20%3D%20%5Cfrac%7B15%7D%7B100%7D%20%3D%200.15)
Test statistic:
![z = \frac{X - \mu}{\frac{\sigma}{\sqrt{n}}}](https://tex.z-dn.net/?f=z%20%3D%20%5Cfrac%7BX%20-%20%5Cmu%7D%7B%5Cfrac%7B%5Csigma%7D%7B%5Csqrt%7Bn%7D%7D%7D)
![z = \frac{0.15 - 0.20}{\frac{0.4}{\sqrt{100}}}](https://tex.z-dn.net/?f=z%20%3D%20%5Cfrac%7B0.15%20-%200.20%7D%7B%5Cfrac%7B0.4%7D%7B%5Csqrt%7B100%7D%7D%7D)
![z = -1.25](https://tex.z-dn.net/?f=z%20%3D%20-1.25)
P-value of the test and decision:
The p-value of the test is the probability of finding a sample proportion below 0.15, which is the p-value of z = -1.25.
Looking at the z-table, z = -1.25 has a p-value of 0.1057.
The p-value of the test is 0.1057 > 0.05, which means that there is not sufficient evidence that fewer than 20% of the museum visitors make use of the device, and so, it should not be withdrawn.
Question ii:
The p-value of the test is 0.1057