Suppose that you wanted to estimate the population mean amount spent eating out per week by Gainesville families. In 2010, a survey found the sample standard deviation was 200 dollars. What size sample would you need to collect in order to make a 95% confidence interval with a margin of error of 15 dollars? O 683 O 27 O783 O 583

MATLAB: An Introduction with Applications
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**Sample Size Determination for Estimating Population Mean**

*Question:*
Suppose that you wanted to estimate the population mean amount spent eating out per week by Gainesville families. In 2010, a survey found the sample standard deviation was 200 dollars. What size sample would you need to collect in order to make a 95% confidence interval with a margin of error of 15 dollars?

*Options:*
- 683
- 27
- 783
- 583

**Explanation:**
 
- The problem involves a sample size calculation for estimating a population mean.
- Given data: 
  - Sample standard deviation (s) = $200 
  - Desired margin of error (E) = $15 
  - Confidence level = 95%

To determine the sample size \[ n \] for a confidence interval, use the formula:

\[ n = \left( \frac{Z \cdot s}{E} \right)^2 \]

Where:
- Z is the Z-value from the standard normal distribution corresponding to the desired confidence level (for a 95% confidence level, Z ≈ 1.96).

By plugging in the given values:

\[ n = \left( \frac{1.96 \cdot 200}{15} \right)^2 \]
\[ n = \left( \frac{392}{15} \right)^2 \]
\[ n \approx (26.13)^2 \]
\[ n \approx 682.75 \]

Rounding up to the nearest integer:

\[ n \approx 683 \]

Hence, the correct answer is:
- 683
Transcribed Image Text:**Sample Size Determination for Estimating Population Mean** *Question:* Suppose that you wanted to estimate the population mean amount spent eating out per week by Gainesville families. In 2010, a survey found the sample standard deviation was 200 dollars. What size sample would you need to collect in order to make a 95% confidence interval with a margin of error of 15 dollars? *Options:* - 683 - 27 - 783 - 583 **Explanation:** - The problem involves a sample size calculation for estimating a population mean. - Given data: - Sample standard deviation (s) = $200 - Desired margin of error (E) = $15 - Confidence level = 95% To determine the sample size \[ n \] for a confidence interval, use the formula: \[ n = \left( \frac{Z \cdot s}{E} \right)^2 \] Where: - Z is the Z-value from the standard normal distribution corresponding to the desired confidence level (for a 95% confidence level, Z ≈ 1.96). By plugging in the given values: \[ n = \left( \frac{1.96 \cdot 200}{15} \right)^2 \] \[ n = \left( \frac{392}{15} \right)^2 \] \[ n \approx (26.13)^2 \] \[ n \approx 682.75 \] Rounding up to the nearest integer: \[ n \approx 683 \] Hence, the correct answer is: - 683
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