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Given data from two samples:

\begin{tabular}{|c|c|c|c|}
\hline
& Size (n) & [tex]$\operatorname{Mean} (x)$[/tex] & [tex]$SD (s)$[/tex] \\
\hline
Sample 1 & 60 & 985 & 8.7 \\
\hline
Sample 2 & 55 & 1300 & 9.6 \\
\hline
\end{tabular}

An official conducts a two-sample t-test to determine whether these data provide significant evidence that students at University 1 are eating less than students at University 2. The test statistic is [tex]$t = 3.2$[/tex] with a [tex]$P$[/tex]-value of 0.0009.

Which of the following is an appropriate conclusion?

A. The samples provide significant evidence that students from Sample 1 are eating less than students from Sample 2.
B. The samples do not provide statistically significant evidence.
C. We cannot use the t-test in this case because the variables (total calories consumed) are likely skewed to the right at each school.


Sagot :

To determine the correct conclusion from the two-sample t-test conducted to compare the eating habits (total calories consumed) of students from two universities, follow these steps:

1. State the Null and Alternative Hypotheses:
- Null Hypothesis (H0): μ1 = μ2, indicating that the mean calorie consumption for students from both universities is the same.
- Alternative Hypothesis (H1): μ1 < μ2, indicating that the mean calorie consumption for students from University 1 (Sample 1) is less than that for University 2 (Sample 2).

2. Given Information:
- Sample 1: n1 = 60, mean1 = 985, sd1 = 8.7
- Sample 2: n2 = 55, mean2 = 1300, sd2 = 9.6
- Test statistic (t) = 3.2
- P-value = 0.0009

3. Significance Level:
- Commonly used significance level (α) = 0.05

4. Decision Rule:
- If the P-value is less than the significance level (α), we reject the null hypothesis.
- If the P-value is greater than or equal to the significance level, we fail to reject the null hypothesis.

5. Compare the P-value with the Significance Level:
- P-value = 0.0009
- Significance level (α) = 0.05

Since 0.0009 < 0.05, we reject the null hypothesis.

6. Conclusion:
Rejecting the null hypothesis provides sufficient evidence to support the alternative hypothesis.

Therefore, the correct conclusion is:
- The samples provide significant evidence that students from Sample 1 are eating less than students from Sample 2.