Answer:
Option <em>B</em> is not the most common correct choice.
Step-by-step explanation:
The multiple-choice questions on Advanced Placement exams have five options: A, B, C, D, and E.
The probability that any of these five option is the correct answer is:
![p=\frac{1}{5}=0.20](https://tex.z-dn.net/?f=p%3D%5Cfrac%7B1%7D%7B5%7D%3D0.20)
A random sample of 400 multiple-choice questions on Advanced Placement exam are selected.
The results showed that 90 of the 400 questions having B as the answer.
To test the hypothesis that option B is more likely the correct answer for most question, the hypothesis can be defined as:
<em>H₀</em>: All the options are equally probable, i.e. <em>p</em> = 0.20.
<em>Hₐ</em>: Option B is more likely the correct option, i.e. <em>p</em> > 0.20.
Compute the sample proportion as follows:
![\hat p=\frac{90}{400}=0.225](https://tex.z-dn.net/?f=%5Chat%20p%3D%5Cfrac%7B90%7D%7B400%7D%3D0.225)
The test statistic is:
![z=\frac{\hat p-p}{\sqrt{\frac{p(1-p)}{n}}}=\frac{0.225-0.20}{\sqrt{\frac{0.20(1-0.20)}{400}}}= 1.25](https://tex.z-dn.net/?f=z%3D%5Cfrac%7B%5Chat%20p-p%7D%7B%5Csqrt%7B%5Cfrac%7Bp%281-p%29%7D%7Bn%7D%7D%7D%3D%5Cfrac%7B0.225-0.20%7D%7B%5Csqrt%7B%5Cfrac%7B0.20%281-0.20%29%7D%7B400%7D%7D%7D%3D%201.25)
The test statistic is 1.25.
Decision rule:
If the <em>p</em>-value of the test is less than the significance level then the null hypothesis will be rejected and vice-versa.
Compute the <em>p</em>-value as follows:
![p-value=P(Z>1.25)\\=1-P(Z](https://tex.z-dn.net/?f=p-value%3DP%28Z%3E1.25%29%5C%5C%3D1-P%28Z%3C1.25%29%5C%5C%3D1-0.89435%5C%5C%3D0.10565%5C%5C%5Capprox%200.1057)
*Use a <em>z</em>-table.
The <em>p</em>-value is 0.1057.
The <em>p</em>-value of the test is quite large. Thus, the null hypothesis was failed to rejected.
Hence, it can be concluded that option <em>B</em> is not the most common correct choice.