# Margin of Error & Sample size

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8. Suppose that it is a presidential election year and Ohio is one of the 'swing' states. Your polling company wants to conduct a presidential preference poll of the citizens of Ohio to predict which candidate will win the election.

a. How many voters must be polled to be 95% confident of your results within +/- 3%?

b. How many voters must be polled to be 95% confident of your results within +/- 2%?

c. How many voters must be polled to be 95% confident of your results within +/- 1%?

d. Discuss the effect of margin of error on sample size.

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The solution provides step by step method for the calculation of margin of error and sample size. Formula for the calculation and Interpretations of the results are also included.

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PROBABILITY

8. Suppose that it is a presidential election year and Ohio is one of the â€œswingâ€ states. Your polling company wants to conduct a presidential preference poll of the citizens of Ohio to predict which candidate will win the election.

Answers

The sample size is given by where p is taken as 0.5

a. How many voters must be polled to be 95% confident of your results within +/- 3%?

Given that E = 3% = 0.03, = 1.959963985

Therefore, ...

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