Math Problem Statement

A publisher reports that 41%41% of their readers own a particular make of car. A marketing executive wants to test the claim that the percentage is actually different from the reported percentage. A random sample of 240240 found that 35%35% of the readers owned a particular make of car. Determine the P-value of the test statistic. Round your answer to four decimal places.

Solution

We are tasked with determining the P-value of the test statistic for the marketing executive's hypothesis test. The null hypothesis (H0H_0) is that the proportion of readers who own the car is the same as reported, i.e., p=0.41p = 0.41, and the alternative hypothesis (HaH_a) is that the true proportion is different, i.e., p0.41p \neq 0.41.

Step 1: Set up the null and alternative hypotheses

  • H0:p=0.41H_0: p = 0.41
  • Ha:p0.41H_a: p \neq 0.41 (two-tailed test)

Step 2: Calculate the test statistic

The test statistic for a proportion is given by the formula: z=p^p0p0(1p0)nz = \frac{\hat{p} - p_0}{\sqrt{\frac{p_0 (1 - p_0)}{n}}} Where:

  • p^\hat{p} = sample proportion = 0.35
  • p0p_0 = population proportion under the null hypothesis = 0.41
  • nn = sample size = 240

Step 3: Plug in the values

z=0.350.410.41(10.41)240z = \frac{0.35 - 0.41}{\sqrt{\frac{0.41(1 - 0.41)}{240}}} Now, let's compute this.The test statistic zz is approximately 1.8899-1.8899.

Step 4: Determine the P-value

Since this is a two-tailed test, the P-value is calculated by finding the area in both tails of the standard normal distribution corresponding to this test statistic.

To find the P-value, we calculate the probability that ZZ is less than 1.8899-1.8899 (and double it, as it's a two-tailed test). Let's compute that next.The P-value is approximately 0.05880.0588 (rounded to four decimal places).

Conclusion:

Since the P-value is 0.05880.0588, it suggests moderate evidence against the null hypothesis at typical significance levels like α=0.05\alpha = 0.05. However, the result is not significant at α=0.05\alpha = 0.05, but it would be significant at α=0.10\alpha = 0.10.

Would you like further details or have any questions?

Here are 5 related questions to expand your understanding:

  1. How is the decision to reject or fail to reject the null hypothesis made using the P-value?
  2. What would happen to the P-value if the sample size were larger?
  3. How does a two-tailed test differ from a one-tailed test?
  4. What are the consequences of using a significance level α=0.10\alpha = 0.10 instead of α=0.05\alpha = 0.05?
  5. How does changing the population proportion p0p_0 affect the test statistic?

Tip: Always define your hypotheses clearly before conducting any hypothesis test to ensure correct interpretation of the results.

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Proportions
Two-tailed Test
P-value

Formulas

z = (p̂ - p₀) / √[p₀(1 - p₀) / n]
P-value for two-tailed test: P(Z < z) * 2

Theorems

Central Limit Theorem (for proportions)
Standard Normal Distribution

Suitable Grade Level

Grades 11-12 / College Level