College

Listed in the accompanying table are waiting times (seconds) of observed cars at a Delaware inspection station. The data from two waiting lines are real observations, and the data from the single waiting line are modeled from those real observations. Assume that the two samples are independent simple random samples selected from normally distributed populations, and do not assume that the population standard deviations are equal. Complete parts (a) and (b).

Click the icon to view the waiting times.

a. Use a 0.01 significance level to test the claim that cars in two queues have a mean waiting time equal to that of cars in a single queue.

Let population 1 correspond to the single waiting line and let population 2 correspond to two waiting lines. What are the null and alternative hypotheses?

A. [tex] H_0: \mu_1 \neq \mu_2 [/tex]
[tex] H_1: \mu_1 = \mu_2 [/tex]

C. [tex] H_0: \mu_1 = \mu_2 [/tex]
[tex] H_1: \mu_1 > \mu_2 [/tex]

**Waiting Times**

[tex]
\[
\begin{array}{|ll|cc|}
\hline
\multicolumn{2}{|c|}{\text{One Line}} & \multicolumn{2}{c|}{\text{Two Lines}} \\
\hline
63.6 & 733.6 & 63.5 & 865.4 \\
157.3 & 606.2 & 215.5 & 1089.8 \\
141.9 & 267.9 & 85.7 & 663.1 \\
278.5 & 310.2 & 339.9 & 518.2 \\
252.7 & 129.2 & 199.7 & 565.8 \\
476.3 & 133.2 & 630.3 & 267.9 \\
477.9 & 122.2 & 332.7 & 350.1 \\
473.6 & 128.8 & 328.6 & 94.8 \\
401.5 & 233.3 & 915.3 & 99.8 \\
721.6 & 460.7 & 552.6 & 162.6 \\
761.3 & 481.6 & 596.7 & 100.6 \\
692.3 & 518.1 & & \\
837.2 & 508.9 & & \\
902.7 & 579.9 & & \\
\hline
\end{array}
\]
[/tex]

Answer :

To address the problem of comparing the mean waiting times between cars in a single waiting line and those in two waiting lines, we will follow these steps:

### Step 1: Define the Hypotheses

We have been asked to determine whether the mean waiting time in a single waiting line (population 1) is equal to the mean waiting time in two waiting lines (population 2). The hypotheses are defined as follows:

- Null Hypothesis ([tex]\(H_0\)[/tex]): The means are equal, [tex]\(\mu_1 = \mu_2\)[/tex].
- Alternative Hypothesis ([tex]\(H_1\)[/tex]): The mean waiting time for the single line is greater than the mean waiting time for the two lines, [tex]\(\mu_1 > \mu_2\)[/tex].

### Step 2: Conduct a Two-Sample t-Test

Since we know that the populations are normally distributed and the population standard deviations are not assumed to be equal, a two-sample t-test for unequal variances (also known as Welch's t-test) is suitable.

### Step 3: Determine the Significance Level

The significance level ([tex]\(\alpha\)[/tex]) for the test is 0.01.

### Step 4: Analyze the Results

After conducting the t-test, we obtained the following results:

- T-statistic: Approximately 0.1595
- P-value (one-tailed): Approximately 0.4370

### Step 5: Decision Rule

In a hypothesis test, we compare the p-value to the significance level:

- If the p-value is less than [tex]\(\alpha\)[/tex] (0.01), we reject the null hypothesis.
- If the p-value is greater than or equal to [tex]\(\alpha\)[/tex], we do not reject the null hypothesis.

### Step 6: Conclusion

With a p-value of approximately 0.4370, which is much greater than the significance level of 0.01, we do not reject the null hypothesis. This indicates that we do not have enough evidence to claim that the mean waiting time in a single waiting line is greater than in two waiting lines.

Therefore, based on the data provided, we cannot conclude a significant difference in the mean waiting times between the two configurations of waiting lines at the 0.01 significance level.

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