Polls and confidence levels

Question

In a recent poll, 201 people were asked if they liked dogs, and 74% said they did. Find the margin of error of this poll, at the 95% confidence level.

Give your answer to three decimals.

Answer 1

Kaelin

Margin of error = z sqrt (p (1-p) / n).

For 95 % confidence interval z = 1.96 (basically you want 2.5% of the area at the right and left end of the normal distribution, needing a z score for an area of 0.975)

p is the observed proportion here 0.74

and n = 201

So you can calculate the margin of error now

Mike