Question

How many people eligible for voting should be included in the survey in order to assure that the radius of a 90% confidence interval for p is no more than 5 confidence

Answer 1

Solution :

Given that,

= 1 - = 0.5

margin of error = E = 5% = 0.05

At 90% confidence level

= 1 - 90%

=1 - 0.90 =0.10

/2 = 0.05

Z/2 = 1.645

sample size = n = (Z _{/ 2} / E )² * * (1 - )

= (1.645 / 0.05)² * 0.5 * 0.5

= 270.60

sample size = n = 271 peoples