Math Problem Statement

Assume that a sample is used to estimate a population proportion p. Find the margin of error E that corresponds to the given statistics and confidence level.

95% confidence; n = 2388, x = 1672

Solution

To calculate the margin of error (E), we use the formula for the margin of error in estimating a population proportion:

E=zp^(1p^)nE = z \cdot \sqrt{\frac{\hat{p}(1 - \hat{p})}{n}}

Step 1: Calculate the sample proportion (p^\hat{p})

p^=xn=167223880.7007\hat{p} = \frac{x}{n} = \frac{1672}{2388} \approx 0.7007

Step 2: Find the critical value (zz) for a 95% confidence level

For a 95% confidence level, the zz-value is approximately 1.96 (from standard normal distribution tables).

Step 3: Calculate the margin of error

Substitute the values into the formula: E=1.960.7007(10.7007)2388E = 1.96 \cdot \sqrt{\frac{0.7007(1 - 0.7007)}{2388}}

First, calculate the variance: 0.7007(10.7007)=0.70070.29930.20980.7007 \cdot (1 - 0.7007) = 0.7007 \cdot 0.2993 \approx 0.2098

Next, divide by the sample size: 0.209823880.0000879\frac{0.2098}{2388} \approx 0.0000879

Take the square root: 0.00008790.00938\sqrt{0.0000879} \approx 0.00938

Multiply by the zz-value: E=1.960.009380.0184E = 1.96 \cdot 0.00938 \approx 0.0184

Final Answer:

The margin of error is approximately: E0.0184or1.84%E \approx 0.0184 \, \text{or} \, 1.84\%


Would you like a breakdown of each step in more detail or have further questions?

Related Questions:

  1. How is the critical zz-value determined for different confidence levels?
  2. What happens to the margin of error if the sample size increases?
  3. How does the sample proportion (p^\hat{p}) influence the margin of error?
  4. Can this formula be used for very small sample sizes? Why or why not?
  5. How do confidence levels higher than 95% affect the margin of error?

Tip:

Always double-check whether the sample size is large enough for the approximation to hold true; np^5n \cdot \hat{p} \geq 5 and n(1p^)5n \cdot (1 - \hat{p}) \geq 5 are common guidelines.

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Math Problem Analysis

Mathematical Concepts

Statistics
Population Proportion
Confidence Interval

Formulas

E = z * sqrt((p(1 - p)) / n)

Theorems

Central Limit Theorem (for approximating population proportion distribution)
Normal Distribution Properties (for z-value determination)

Suitable Grade Level

College Level (Introductory Statistics)