Math Problem Statement

Suppose a simple random sample of size

nequals=150150

is obtained from a population whose size is

Upper N equals 25 comma 000N=25,000

and whose population proportion with a specified characteristic is

p equals 0.6 .p=0.6.****

Complete parts ​(a)**** through​ (c)****

below**.**

Question content area bottom

Part 1

​(a) Describe the sampling distribution of

ModifyingAbove p with caretp.

Choose the phrase that best describes the shape of the sampling distribution below.

A.

Approximately normal because

n less than or equals 0.05 Upper Nn≤0.05N

and np left parenthesis 1 minus p right parenthesis greater than or equals 10.np(1−p)≥10.

Your answer is correct.

B.

Not normal because

n less than or equals 0.05 Upper Nn≤0.05N

and np left parenthesis 1 minus p right parenthesis less than 10.np(1−p)<10.

C.

Not normal because

n less than or equals 0.05 Upper Nn≤0.05N

and np left parenthesis 1 minus p right parenthesis greater than or equals 10.np(1−p)≥10.

D.

Approximately normal because

n less than or equals 0.05 Upper Nn≤0.05N

and np left parenthesis 1 minus p right parenthesis less than 10.np(1−p)<10.

Part 2

Determine the mean of the sampling distribution of

ModifyingAbove p with caretp.

mu Subscript ModifyingAbove p with caret Baseline equalsμp=0.60.6

​(Round to one decimal place as​ needed.)

Part 3

Determine the standard deviation of the sampling distribution of

ModifyingAbove p with caretp.

sigma Subscript ModifyingAbove p with caretσpequals=enter your response here

​(Round to six decimal places as​ needed.)

Solution

Part 1: Describe the sampling distribution of p^\hat{p}

To determine the shape of the sampling distribution, we need to check two conditions:

  1. Condition 1: The sample size nn should be less than or equal to 5% of the population size NN:

    n0.05Nn \leq 0.05N Here, n=150n = 150 and N=25,000N = 25,000. Check if this condition holds:

    1500.05(25,000)150 \leq 0.05(25,000)

    1501,250150 \leq 1,250

    This condition is satisfied.

  2. Condition 2: The product np(1p)np(1-p) should be greater than or equal to 10:

    np(1p)10np(1 - p) \geq 10 Here, n=150n = 150 and p=0.6p = 0.6. Check if this condition holds:

    150×0.6×(10.6)=150×0.6×0.4=36150 \times 0.6 \times (1 - 0.6) = 150 \times 0.6 \times 0.4 = 36

    Since 36 is greater than 10, this condition is also satisfied.

Thus, since both conditions are satisfied, the sampling distribution of p^\hat{p} is approximately normal. The correct choice is:

A. Approximately normal because n0.05Nn \leq 0.05N and np(1p)10np(1-p) \geq 10.


Part 2: Determine the mean of the sampling distribution of p^\hat{p}

The mean of the sampling distribution of p^\hat{p} is equal to the population proportion pp.

μp^=p=0.6\mu_{\hat{p}} = p = 0.6

So, the mean is 0.60.6.


Part 3: Determine the standard deviation of the sampling distribution of p^\hat{p}

The standard deviation of the sampling distribution of p^\hat{p} is given by the formula:

σp^=p(1p)n×NnN1\sigma_{\hat{p}} = \sqrt{\frac{p(1 - p)}{n}} \times \sqrt{\frac{N - n}{N - 1}}

Where:

  • p=0.6p = 0.6
  • n=150n = 150
  • N=25,000N = 25,000

First, calculate the first part:

σp^=0.6(10.6)150=0.6×0.4150=0.24150=0.0016=0.04\sigma_{\hat{p}} = \sqrt{\frac{0.6(1 - 0.6)}{150}} = \sqrt{\frac{0.6 \times 0.4}{150}} = \sqrt{\frac{0.24}{150}} = \sqrt{0.0016} = 0.04

Now, account for the finite population correction factor:

Correction factor=NnN1=25,00015025,0001=24,85024,9990.99400.9970\text{Correction factor} = \sqrt{\frac{N - n}{N - 1}} = \sqrt{\frac{25,000 - 150}{25,000 - 1}} = \sqrt{\frac{24,850}{24,999}} \approx \sqrt{0.9940} \approx 0.9970

Finally, multiply the two values:

σp^0.04×0.9970=0.03988\sigma_{\hat{p}} \approx 0.04 \times 0.9970 = 0.03988

Rounding to six decimal places:

σp^0.039880\sigma_{\hat{p}} \approx 0.039880


Summary:

  1. Part 1 Answer: A. Approximately normal.
  2. Part 2 Answer: μp^=0.6\mu_{\hat{p}} = 0.6
  3. Part 3 Answer: σp^0.039880\sigma_{\hat{p}} \approx 0.039880

Would you like further clarification on any part? Here are some related questions to explore:

  1. What happens to the sampling distribution when the sample size increases?
  2. How would the sampling distribution change if the population proportion pp was closer to 0 or 1?
  3. Why do we apply a finite population correction factor in the standard deviation formula?
  4. What is the impact of ignoring the finite population correction factor in this scenario?
  5. How can the normal approximation be used in hypothesis testing with sample proportions?

Tip: Always check both conditions (sample size and proportion criteria) when determining if the sampling distribution of a sample proportion is approximately normal.

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Math Problem Analysis

Mathematical Concepts

Statistics
Sampling Distributions
Proportions

Formulas

Sampling distribution mean: μ̂p = p
Standard deviation of sampling distribution: σ̂p = sqrt[p(1 - p) / n] * sqrt[(N - n) / (N - 1)]

Theorems

Central Limit Theorem
Finite Population Correction Factor

Suitable Grade Level

Undergraduate Statistics