Welcome to Westonci.ca, where you can find answers to all your questions from a community of experienced professionals. Connect with professionals on our platform to receive accurate answers to your questions quickly and efficiently. Explore comprehensive solutions to your questions from knowledgeable professionals across various fields on our platform.

Based on a sample of 40 people, the sample mean GPA was 3.14 with a standard deviation of 0.07
The p-value is?
The significance level is?

Sagot :

To find the p-value and the significance level, we need to perform a hypothesis test. Let's assume we are testing the hypothesis that the population mean GPA is different from a certain value (let's say 3.0 for this example).

1. **Hypothesis Setup:**
- Null Hypothesis (\(H_0\)): \(\mu = 3.0\)
- Alternative Hypothesis (\(H_a\)): \(\mu \neq 3.0\)

2. **Test Statistic:**
We use the t-test for the sample mean since the population standard deviation is unknown. The test statistic is calculated as follows:

\[
t = \frac{\bar{x} - \mu}{s / \sqrt{n}}
\]

Where:
- \(\bar{x} = 3.14\) (sample mean)
- \(\mu = 3.0\) (hypothesized population mean)
- \(s = 0.07\) (sample standard deviation)
- \(n = 40\) (sample size)

Plugging in the values:

\[
t = \frac{3.14 - 3.0}{0.07 / \sqrt{40}} = \frac{0.14}{0.01107} \approx 12.64
\]

3. **Degrees of Freedom:**
The degrees of freedom (df) for this test is \( n - 1 = 40 - 1 = 39 \).

4. **P-Value:**
Using a t-distribution table or a calculator, we find the p-value corresponding to the calculated t-value (12.64) with 39 degrees of freedom.

Given the large t-value, the p-value will be extremely small (close to 0). For practical purposes, it is often reported as \( p < 0.0001 \).

5. **Significance Level:**
The significance level (\(\alpha\)) is typically chosen by the researcher before conducting the test. Common significance levels are 0.05, 0.01, or 0.001.

If not specified, we can assume a common significance level such as 0.05.

**Conclusion:**
- The p-value is extremely small ( \( p < 0.0001 \) ).
- If the significance level is 0.05, we reject the null hypothesis since the p