Solve your doubts and expand your knowledge with IDNLearn.com's extensive Q&A database. Our experts provide timely, comprehensive responses to ensure you have the information you need.

The work week for adults in the US that work full-time is normally distributed with a mean of 47 hours. A newly hired engineer at a start-up company believes that employees at start-up companies work more on average than most working adults in the US. She asks 12 engineering friends at start-ups for the lengths in hours of their work week. Their responses are shown in the table below. Test the claim using a [tex]1\%[/tex] level of significance.

\begin{tabular}{|c|}
\hline
Hours \\
\hline
50 \\
\hline
40 \\
\hline
50 \\
\hline
53 \\
\hline
47 \\
\hline
68 \\
\hline
45 \\
\hline
59 \\
\hline
45 \\
\hline
48 \\
\hline
52 \\
\hline
55 \\
\hline
\end{tabular}

What are the correct hypotheses?
[tex]H_0[/tex]: [tex]\mu = 47[/tex] hours
[tex]H_a[/tex]: [tex]\mu \ \textgreater \ 47[/tex] hours

Based on the hypotheses, find the following:

Test Statistic [tex]= \square[/tex] (Give answer to at least 4 decimal places.)
[tex]p[/tex]-value [tex]= \square[/tex] (Give answer to at least 4 decimal places.)

The correct decision is to [tex]\square[/tex] (Select an answer).

The correct summary would be: (Select an answer) that the mean number of hours of all employees at start-up companies work more than the US mean of 47 hours.


Sagot :

Let's go through the solution step-by-step to test the claim using a [tex]\(1\% \)[/tex] level of significance.

1. Formulating the Hypotheses:

The null hypothesis ([tex]\(H_0\)[/tex]) and the alternative hypothesis ([tex]\(H_a\)[/tex]) are:
[tex]\[ H_0: \mu \leq 47 \text{ hours} \][/tex]
[tex]\[ H_a: \mu > 47 \text{ hours} \][/tex]
Here, [tex]\( \mu \)[/tex] represents the mean number of hours employees at start-up companies work per week.

2. Given Data:
[tex]\[ \text{Sample Data (in hours): } 50, 40, 50, 53, 47, 68, 45, 59, 45, 48, 52, 55 \][/tex]
[tex]\[ \text{Sample Size (n): } 12 \][/tex]
[tex]\[ \text{Population Mean (} \mu_0 \text{): } 47 \text{ hours} \][/tex]
[tex]\[ \text{Level of Significance (} \alpha \text{): } 0.01 \][/tex]

3. Calculating Sample Mean:
[tex]\[ \text{Sample Mean (} \bar{x} \text{): } 51.0 \text{ hours} \][/tex]

4. Calculating Sample Standard Deviation:
[tex]\[ \text{Sample Standard Deviation (s): } 7.3485 \][/tex]

5. Calculating the Test Statistic:
The test statistic for a one-sample t-test is calculated by:
[tex]\[ t = \frac{\bar{x} - \mu_0}{\frac{s}{\sqrt{n}}} \][/tex]
Plugging in the values:
[tex]\[ t = \frac{51.0 - 47}{\frac{7.3485}{\sqrt{12}}} = 1.8856 \][/tex]

6. Degrees of Freedom:
[tex]\[ \text{Degrees of Freedom (df): } n - 1 = 12 - 1 = 11 \][/tex]

7. Finding the p-value:

Using the test statistic and the degrees of freedom, we can find the p-value associated with a one-tailed test.
[tex]\[ p\text{-value} = 0.0430 \][/tex]

8. Decision Making:

Since the p-value [tex]\( (0.0430) \)[/tex] is greater than the level of significance [tex]\( (0.01) \)[/tex]:

- We fail to reject the null hypothesis [tex]\( H_0 \)[/tex].

The correct decision is to "Fail to reject the null hypothesis."

9. Summary:

Based on the results, "There is insufficient evidence to conclude that the mean number of hours of all employees at start-up companies work more than the US mean of 47 hours."

### Summary of the Solution:
- Hypotheses:
[tex]\( H_0: \mu = 47 \text{ hours} \)[/tex]
[tex]\( H_a: \mu > 47 \text{ hours} \)[/tex]

- Test Statistic: [tex]\( t = 1.8856 \)[/tex]
- p-value: [tex]\( 0.0430 \)[/tex]

- Decision: "Fail to reject the null hypothesis."
- Correct Summary: "There is insufficient evidence to conclude that the mean number of hours of all employees at start-up companies work more than the US mean of 47 hours."