Answer :
The survey has a margin of error of +/- 3.4 percentage points, and for an 86% confidence interval with a sample size of 1500, the margin of error is about 2.6 percentage points.
The last sentence of the quote means that the margin of error for the survey is +/- 3.4 percentage points. This indicates that the estimated proportions of votes for each political party may vary by up to 3.4 percentage points from the actual proportions in the population.
To calculate the standard error, we use the formula:
Standard Error = √(P * (1 - P) / n)
where:
P = estimated proportion (sample proportion)
n = sample size
Given that the estimated proportion (P) is not provided in the quote, we cannot calculate the standard error without additional information.
To find the margin of error for an 86% confidence interval (C.I.) with a sample size of 1500, we can use the formula:
Margin of Error = Z * √(P * (1 - P) / n)
where:
Z = Z-score corresponding to the desired confidence level (86% confidence level in this case)
P = estimated proportion (sample proportion)
n = sample size
For an 86% confidence level, the Z-score is approximately 1.0803 (corresponding to the 43rd percentile of the standard normal distribution).
Assuming P = 0.5 (which gives the maximum margin of error for a given sample size),
Margin of Error = 1.0803 * √(0.5 * (1 - 0.5) / 1500)
Margin of Error ≈ 0.026 or 2.6 percentage points (rounded to two decimal places)
So, the margin of error for the 86% confidence interval with a sample size of 1500 would be approximately 2.6 percentage points.
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