Question

The margin of error means that if this poll were conducted many times, we would expect that at least 95% of the time the actual number of people in the population that would give a particular response is somewhere between  - the margin of error and  + the margin of error.  - the margin of error and  + the margin of error.

3.On December 18, 2015, an organization called Public Policy Polling released the results of a poll with 532 responses. Of those respondents, 181 supported one particular candidate for the presidency in 2016. Among those folks, 41% were in favor of bombing Agrabah, which as it turns out is the fictional country from the Disney movie Aladdin.Use the formula in the colored box to find the margin of error for this result.

Answer 1

The events of poll are either supporting the particular candidate or not supporting.

Therefore this is a binomial event where

X: No. of people supporting the candidate.

Where = 181 / 532 = 0.3402

   =1 - 0.95 = 0.05

Therefore the critical value at

= Z_0.025

= 1.96 .............using normal percentage tables with p = 0.025

Margin of error = Critical value * SE

= *       

Subsitute the values

Ans: 0.04026

Confidence interval

(1- )% CI for population proportion

    

(0.3402 + - 0.04026)

We are 95% confident the true popultion proportion is within 4.03% of the sample proportion of 34.02%.