Math Problem Statement

Conduct a hypothesis test. Include all the steps.

  1. An instructor claims that 60% of her students go through life feeling more enriched. To test this claim you interview 64 of her former students and find that 30 felt more enriched. At the 2% level of significance, test the claim. (critical value method)

Solution

To conduct a hypothesis test using the critical value method, we’ll follow these steps:

Step 1: State the hypotheses

  • Null Hypothesis (H₀): p=0.60p = 0.60 (The true proportion of students who feel enriched is 60%.)
  • Alternative Hypothesis (H₁): p0.60p \neq 0.60 (The true proportion of students who feel enriched is not 60%.)

This is a two-tailed test since we are testing whether the proportion is different from 60%, not specifically greater than or less than 60%.

Step 2: Determine the significance level

The significance level, α\alpha, is given as 0.02 (or 2%).

Step 3: Calculate the test statistic

We’ll use the test statistic for proportions: z=p^p0p0(1p0)nz = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0 (1 - p_0)}{n}}} where:

  • p^\hat{p} is the sample proportion,
  • p0p_0 is the hypothesized population proportion,
  • nn is the sample size.

Given dataTo conduct a hypothesis test using the critical value method, we’ll follow these steps:

Step 1: State the hypotheses

  • Null Hypothesis (H₀): p=0.60p = 0.60 (The true proportion of students who feel enriched is 60%.)
  • Alternative Hypothesis (H₁): p0.60p \neq 0.60 (The true proportion of students who feel enriched is not 60%.)

This is a two-tailed test since we are testing whether the proportion is different from 60%, not specifically greater than or less than 60%.

Step 2: Determine the significance level

The significance level, α\alpha, is given as 0.02 (or 2%).

Step 3: Calculate the test statistic

We’ll use the test statistic for proportions: z=p^p0p0(1p0)nz = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0 (1 - p_0)}{n}}} where:

  • p^\hat{p} is the sample proportion,
  • p0p_0 is the hypothesized population proportion,
  • nn is the sample size.

Given

  • n=64n = 64 (sample size),
  • p0=0.60p_0 = 0.60 (claimed proportion),
  • x=30x = 30 (number of students who felt enriched).

Calculate the sample proportion p^\hat{p}: p^=xn=3064=0.46875\hat{p} = \frac{x}{n} = \frac{30}{64} = 0.46875

Now, calculate the standard deviation for the sampling distribution: σp^=p0(1p0)n=0.60×0.4064=0.003750.06124\sigma_{\hat{p}} = \sqrt{\frac{p_0 (1 - p_0)}{n}} = \sqrt{\frac{0.60 \times 0.40}{64}} = \sqrt{0.00375} \approx 0.06124

Calculate the zz-score: z=p^p0σp^=0.468750.600.061242.14z = \frac{\hat{p} - p_0}{\sigma_{\hat{p}}} = \frac{0.46875 - 0.60}{0.06124} \approx -2.14

Step 4: Determine the critical value

Since we have a two-tailed test at a significance level of α=0.02\alpha = 0.02, we’ll divide this by 2 to find the critical values for both tails.

  • For α/2=0.01\alpha/2 = 0.01, the critical zz-values (from a standard normal table) are approximately ±2.33\pm 2.33.

Step 5: Make a decision

  • Decision rule: If z>2.33|z| > 2.33, reject the null hypothesis.
  • Test statistic: z2.14z \approx -2.14.

Since z=2.14|z| = 2.14 is less than 2.33, we do not reject the null hypothesis.

Step 6: Conclusion

At the 2% level of significance, there is not enough evidence to reject the instructor's claim that 60% of her students feel more enriched.


Would you like more details or have any questions?

Here are some related questions you might explore:

  1. How does changing the sample size affect the result of the hypothesis test?
  2. What happens if we use a different significance level, like 5% or 1%?
  3. How would a one-tailed test differ in this scenario?
  4. Why is it necessary to use a two-tailed test here?
  5. How can the confidence interval help in interpreting the results of this test?

Tip: Always check if the sample size meets conditions for normal approximation in a hypothesis test for proportions.

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Proportions
Critical Value Method

Formulas

z = (\hat{p} - p_0) / sqrt(p_0 * (1 - p_0) / n)
\hat{p} = x / n

Theorems

Central Limit Theorem (for large sample sizes)
Z-test for Proportions

Suitable Grade Level

Grades 11-12