Math Problem Statement

Your statistics instructor claims that 60 percent of the students who take her Elementary Statistics class go through life feeling more enriched. For some reason that she can't quite figure out, most people don't believe her. You decide to check this out on your own. You randomly survey 64 of her past Elementary Statistics students and find that 34 feel more enriched as a result of her class. Now, what do you think?

Solution

To evaluate the instructor's claim, we can perform a hypothesis test for a population proportion. Here are the steps to determine whether the sample data supports the instructor's claim that 60% of her students feel enriched.


Step 1: Formulate the Hypotheses

  • Null Hypothesis (H0H_0): p=0.60p = 0.60
    (The proportion of students who feel enriched is 60%.)
  • Alternative Hypothesis (HaH_a): p0.60p \neq 0.60
    (The proportion of students who feel enriched is different from 60%.)

Step 2: Check the Sample Data

  • Sample size (nn) = 64
  • Number of students feeling enriched (xx) = 34
  • Sample proportion (p^\hat{p}) = xn=3464=0.53125\frac{x}{n} = \frac{34}{64} = 0.53125.

Step 3: Determine the Test Statistic

We will use the z-test for proportions:

z=p^p0p0(1p0)nz = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0(1-p_0)}{n}}}

Where:

  • p0=0.60p_0 = 0.60 (hypothesized population proportion)
  • p^=0.53125\hat{p} = 0.53125 (sample proportion)

Substituting values:

z=0.531250.600.60(10.60)64z = \frac{0.53125 - 0.60}{\sqrt{\frac{0.60(1-0.60)}{64}}}

z=0.068750.2464z = \frac{-0.06875}{\sqrt{\frac{0.24}{64}}}

z=0.068750.061251.12z = \frac{-0.06875}{0.06125} \approx -1.12


Step 4: Determine the Critical Value and p-value

For a two-tailed test at a 5% significance level (α=0.05\alpha = 0.05), the critical z-values are approximately ±1.96\pm 1.96.

  • Using standard z-tables, the p-value for z=1.12z = -1.12 is approximately 0.263.

Step 5: Make a Decision

  • Since z=1.12z = -1.12 falls within the range [1.96,1.96][-1.96, 1.96], and the p-value (0.263) is greater than α=0.05\alpha = 0.05, we fail to reject the null hypothesis.

Conclusion

The data does not provide sufficient evidence to conclude that the true proportion of students feeling enriched is different from 60%. The instructor's claim could be reasonable based on this analysis.


Do you want further details or have any questions?
Here are some related questions for exploration:

  1. What is the meaning of a p-value in hypothesis testing?
  2. How would the conclusion change if the sample size were larger?
  3. What would happen if we conducted a one-tailed test instead?
  4. How does changing the significance level (α\alpha) affect the results?
  5. Could other factors, like survey bias, influence these results?

Tip: Always check if the sample size is large enough to justify using normal approximation for a proportion test. For this test, np010n \cdot p_0 \geq 10 and n(1p0)10n \cdot (1 - p_0) \geq 10 should hold true!

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Population Proportion
Statistical Significance

Formulas

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

Theorems

Central Limit Theorem
Properties of Normal Distribution

Suitable Grade Level

Undergraduate Level (Statistics Course)