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A poll of 120 adults who shopped at Walmart found that 54 have purchased a flat screen television.

Based on these data, what is the margin of error for a 95% confidence interval of the proportion of adults who have purchased a flat screen television?

A. 0.45

B. 0.0454

C. 0.075

D. 0.089

1 Answer

3 votes

Final answer:

The margin of error for a 95% confidence interval based on a survey where 54 out of 120 adults purchased a flat screen television is calculated using a specific formula yielding a result of approximately 0.089. Option D is the correct answer.

Step-by-step explanation:

The student is asked to calculate the margin of error for a 95% confidence interval of the proportion of adults who have purchased a flat screen television, based on a survey of 120 adults at Walmart in which 54 reported having made such a purchase.

To calculate the margin of error, the following formula is used:

]Margin of Error = Z * sqrt((p*(1-p))/n)

where:

  • Z is the z-score corresponding to the desired confidence level (1.96 for 95%)
  • p is the sample proportion (54/120)
  • n is the sample size (120)

Plugging in the values, we get:

Margin of Error = 1.96 * sqrt((0.45*(1-0.45))/120) = 1.96 * sqrt((0.45*0.55)/120) = 1.96 * sqrt(0.2475/120) = 1.96 * sqrt(0.0020625) = 1.96 * 0.0454 ≈ 0.089

Therefore, the correct answer is D. 0.089.

User Lionel B
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