Math Problem Statement

One study claimed that 94% 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 277 college students and finds that 254 of them identify themselves as procrastinators. Does this evidence support the professor’s claim that fewer than 94% 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 compute the value of the test statistic, we will use the z-test for a population proportion since we are testing a proportion against a hypothesized value. The formula for the test statistic is:

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

Step-by-Step Calculation:

  1. Define the variables:

    • Sample proportion (p^\hat{p}):
      p^=number of procrastinators in the samplesample size=2542770.9162\hat{p} = \frac{\text{number of procrastinators in the sample}}{\text{sample size}} = \frac{254}{277} \approx 0.9162
    • Hypothesized population proportion (p0p_0): 0.940.94
    • Sample size (nn): 277277
  2. Calculate the standard error: SE=p0(1p0)n=0.94(10.94)277=0.94×0.062770.000203850.01429\text{SE} = \sqrt{\frac{p_0(1 - p_0)}{n}} = \sqrt{\frac{0.94(1 - 0.94)}{277}} = \sqrt{\frac{0.94 \times 0.06}{277}} \approx \sqrt{0.00020385} \approx 0.01429

  3. Compute the test statistic: z=p^p0SE=0.91620.940.014290.02380.014291.67z = \frac{\hat{p} - p_0}{\text{SE}} = \frac{0.9162 - 0.94}{0.01429} \approx \frac{-0.0238}{0.01429} \approx -1.67

Final Answer:

The value of the test statistic is approximately: z=1.67z = -1.67

Let me know if you have any questions or would like to proceed with further steps in this hypothesis test!


Here are 5 questions to deepen your understanding:

  1. What is the significance of the hypothesized proportion (p0p_0) in this context?
  2. Why do we use a z-test instead of a t-test for proportions?
  3. How does the sample size affect the standard error and test statistic?
  4. What role does the significance level (α=0.10\alpha = 0.10) play in interpreting the results?
  5. What conclusion would you draw if the calculated zz-value fell inside the critical region?

Tip: Always check assumptions of the z-test (large sample size and independent observations) before applying it.

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Population Proportions
Z-Test

Formulas

z = (p_hat - p_0) / sqrt(p_0(1 - p_0) / n)

Theorems

Central Limit Theorem

Suitable Grade Level

College Level