Math Problem Statement

According to a survey in a country, 37% of adults do not own a credit card. Suppose a simple random sample of 500 adults is obtained. Describe the sampling distribution of p̂, the sample proportion of adults who do not own a credit card, and determine the mean of the sampling distribution of p̂.

Solution

Let's analyze the problem step-by-step.

Part (a): Describe the Sampling Distribution

The question states:

  • 37% of adults do not own a credit card, so p=0.37p = 0.37.
  • A sample of 500 adults is taken, so n=500n = 500.

We need to determine whether the sampling distribution of p^\hat{p} (the sample proportion) is approximately normal.

To verify if the sampling distribution of p^\hat{p} is approximately normal, we check two conditions:

  1. Large sample condition: n0.05Nn \geq 0.05N (where NN is the population size, typically large).
  2. Success-failure condition: Both np10np \geq 10 and n(1p)10n(1 - p) \geq 10.

Calculating:

  • np=500×0.37=185np = 500 \times 0.37 = 185 (which is greater than 10).
  • n(1p)=500×(10.37)=500×0.63=315n(1 - p) = 500 \times (1 - 0.37) = 500 \times 0.63 = 315 (also greater than 10).

Both conditions are satisfied, so the sampling distribution of p^\hat{p} is approximately normal.

Thus, Option A is correct: "Approximately normal because n0.05Nn \geq 0.05N and np(1p)10np(1 - p) \geq 10."


Part (b): Determine the Mean of the Sampling Distribution of p^\hat{p}

The mean of the sampling distribution of p^\hat{p} is given by: μp^=p\mu_{\hat{p}} = p

Since p=0.37p = 0.37, we have: μp^=0.37\mu_{\hat{p}} = 0.37

So, the mean of the sampling distribution of p^\hat{p} is 0.37.


Would you like further explanation on these calculations or details on how sampling distributions work?

Related Questions

  1. How is the standard deviation of the sampling distribution of p^\hat{p} calculated?
  2. What is the significance of the success-failure condition in determining normality?
  3. How does sample size affect the shape of the sampling distribution?
  4. Can the sampling distribution of p^\hat{p} ever be exactly normal?
  5. How would the results change if pp were closer to 0 or 1?

Tip

When verifying the normality of a sampling distribution of a proportion, always check both the sample size and the success-failure conditions to ensure accurate results.

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Math Problem Analysis

Mathematical Concepts

Sampling Distribution
Normal Approximation
Proportion

Formulas

Mean of sampling distribution of p̂: μ_p̂ = p
Normality condition: np ≥ 10 and n(1 - p) ≥ 10

Theorems

Central Limit Theorem

Suitable Grade Level

College Statistics