Math Problem Statement

Test the claim that the proportion of people who are confident is smaller than 50% at the 0.10 significance level. The data includes a sample proportion of 41% (0.41) from a sample size of 800.

Solution

From the uploaded image, it appears that the question involves hypothesis testing for the proportion of investors who are confident in meeting their goals. Here’s a detailed breakdown:

Problem Setup

  1. Claim: The proportion of investors who are confident is less than 50%.
  2. Sample Proportion: p^=0.41\hat{p} = 0.41 (41%).
  3. Sample Size: n=800n = 800.
  4. Significance Level: α=0.10\alpha = 0.10.

Hypotheses

  • Null Hypothesis (H0H_0): p=0.50p = 0.50.
  • Alternative Hypothesis (HaH_a): p<0.50p < 0.50 (left-tailed test).

Test Statistic

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

Plugging in the values: z=0.410.500.500.50800z = \frac{0.41 - 0.50}{\sqrt{\frac{0.50 \cdot 0.50}{800}}} z=0.090.25800=0.090.017685.091z = \frac{-0.09}{\sqrt{\frac{0.25}{800}}} = \frac{-0.09}{0.01768} \approx -5.091

P-Value

Using the standard normal table (Z-table), the p-value corresponding to z=5.091z = -5.091 is approximately 0.00000.0000, as the value is extremely small.

Conclusion

Since the p-value (0.00000.0000) is less than α=0.10\alpha = 0.10, we reject the null hypothesis. This supports the claim that the proportion of confident investors is less than 50%.


Would you like further clarification or additional details about hypothesis testing or this specific question? Here are five related questions to expand your understanding:

  1. How do we interpret a p-value in hypothesis testing?
  2. Why do we use a Z-test for proportions, and what are the assumptions?
  3. What happens if the sample size nn is smaller—how does it affect the result?
  4. How does the choice of significance level α\alpha affect hypothesis test conclusions?
  5. What is the difference between left-tailed, right-tailed, and two-tailed tests?

Tip

When conducting hypothesis tests, always check if the sample size is sufficiently large to justify the use of the normal approximation for proportions (np010np_0 \geq 10 and n(1p0)10n(1 - p_0) \geq 10).

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Math Problem Analysis

Mathematical Concepts

Hypothesis Testing
Proportions
Z-Test
Significance Levels

Formulas

z = (p̂ - p₀) / √(p₀(1 - p₀) / n)
p-value calculation from Z-statistic

Theorems

Central Limit Theorem for Proportions

Suitable Grade Level

College Level