Math Problem Statement

One study claimed that 85% of college students identify themselves as procrastinators. A professor believes that the claim regarding college students is too high. The professor conducts a simple random sample of 164 college students and finds that 132 of them identify themselves as procrastinators. Does this evidence support the professor’s claim that fewer than 85% of college students are procrastinators? Use a 0.10 level of significance. Step 2 of 3: Compute the value of the test statistic. Round your answer to two decimal places.

Solution

To test whether the claim of 85% of college students being procrastinators is too high, we perform a hypothesis test for proportions. In this case, we are testing if fewer than 85% of college students identify as procrastinators.

Step 1: Set up the hypotheses

The null hypothesis (H0H_0) and the alternative hypothesis (H1H_1) are as follows:

  • Null hypothesis (H0H_0): p=0.85p = 0.85 (the true proportion of procrastinators is 85%).
  • Alternative hypothesis (H1H_1): p<0.85p < 0.85 (the true proportion of procrastinators is less than 85%).

Step 2: Calculate the test statistic

The test statistic for a proportion is calculated using the z-test formula:

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 population proportion (in this case, 0.85),
  • nn is the sample size.

Given:

  • Sample size (nn) = 164,
  • Number of students who identify as procrastinators = 132,
  • Sample proportion (p^\hat{p}) = 132164\frac{132}{164},
  • Population proportion (p0p_0) = 0.85.

Step 3: Compute the sample proportion

p^=132164=0.8049\hat{p} = \frac{132}{164} = 0.8049

Step 4: Plug the values into the z-test formula

z=0.80490.850.85(10.85)164z = \frac{0.8049 - 0.85}{\sqrt{\frac{0.85(1 - 0.85)}{164}}}

First, calculate the denominator:

0.85(10.85)164=0.85×0.15164=0.1275164=0.0007760.02786\sqrt{\frac{0.85(1 - 0.85)}{164}} = \sqrt{\frac{0.85 \times 0.15}{164}} = \sqrt{\frac{0.1275}{164}} = \sqrt{0.000776} \approx 0.02786

Now, compute the z-value:

z=0.80490.850.02786=0.04510.027861.62z = \frac{0.8049 - 0.85}{0.02786} = \frac{-0.0451}{0.02786} \approx -1.62

Step 5: Conclusion

The value of the test statistic is -1.62.

Would you like to proceed with the next steps to make a conclusion about the hypothesis test or need further clarification?

Ask a new question for Free

By Image

Drop file here or Click Here to upload

Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Proportions
Z-Test

Formulas

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

Theorems

Z-Test for Proportions

Suitable Grade Level

College Level (Statistics)