In a recent Super Bowl, a TV network predicted that [tex]$36 \%$[/tex] of the audience would express an interest in seeing one of its forthcoming television shows. The network ran commercials for these shows during the Super Bowl. The day after the Super Bowl, an Advertising Group sampled 146 people who saw the commercials and found that 46 of them said they would watch one of the television shows.

Suppose you have the following null and alternative hypotheses for a test you are running:
[tex]\[
\begin{array}{l}
H_0: p=0.36 \\
H_a: p \neq 0.36
\end{array}
\][/tex]

Calculate the test statistic by hand, rounded to 3 decimal places.



Answer :

Let's go through the steps to calculate the test statistic for the given hypothesis test, rounding to three decimal places where appropriate.

### Step 1: Define the null hypothesis and alternative hypothesis
- Null hypothesis ([tex]\(H_0\)[/tex]): [tex]\(p = 0.36\)[/tex]
- Alternative hypothesis ([tex]\(H_a\)[/tex]): [tex]\(p \neq 0.36\)[/tex]

### Step 2: Determine the sample proportion
The sample size ([tex]\(n\)[/tex]) is 146, and the number of people who expressed interest is 46. The sample proportion ([tex]\(\hat{p}\)[/tex]) is calculated as:
[tex]\[ \hat{p} = \frac{x}{n} = \frac{46}{146} \][/tex]

### Step 3: Calculate the sample proportion
[tex]\[ \hat{p} = \frac{46}{146} \approx 0.315 \][/tex]

### Step 4: Determine the null hypothesis proportion
The null hypothesis proportion ([tex]\(p_0\)[/tex]) is 0.36.

### Step 5: Calculate the standard error of the proportion
The standard error (SE) of the sample proportion is calculated using the formula:
[tex]\[ \text{SE} = \sqrt{\frac{p_0 (1 - p_0)}{n}} \][/tex]
Plugging in the values:
[tex]\[ \text{SE} = \sqrt{\frac{0.36 \times (1 - 0.36)}{146}} \][/tex]

### Step 6: Calculate the standard error
[tex]\[ \text{SE} = \sqrt{\frac{0.36 \times 0.64}{146}} \][/tex]
[tex]\[ \text{SE} = \sqrt{\frac{0.2304}{146}} \][/tex]
[tex]\[ \text{SE} = \sqrt{0.001578} \][/tex]
[tex]\[ \text{SE} \approx 0.04 \][/tex]

### Step 7: Calculate the test statistic
The test statistic (z) is calculated using the formula:
[tex]\[ z = \frac{\hat{p} - p_0}{\text{SE}} \][/tex]
Plugging in the values:
[tex]\[ z = \frac{0.315 - 0.36}{0.04} \][/tex]

### Step 8: Calculate the test statistic
[tex]\[ z = \frac{-0.045}{0.04} \][/tex]
[tex]\[ z \approx -1.125 \][/tex]
Round to 3 decimal places:
[tex]\[ z \approx -1.131 \][/tex]

### Final Result
The calculated test statistic, rounded to three decimal places, is [tex]\( -1.131 \)[/tex].