Question

In a recent poll, 250 people were asked if they liked dogs, and 17% said they did. Find the margin of error of this poll, at the 99% confidence level. Give your answer to three decimals

Answer 1

Solution :

Given that,

n = 250

Point estimate = sample proportion = = 0.17

1 -   = 1-0.17 =0.83

At 99% confidence level the z is ,

  = 1 - 99% = 1 - 0.99 = 0.01

/ 2 = 0.01 / 2 = 0.005

Z/2 = Z0.005 = 2.576 ( Using z table )

  Margin of error = E =   Z / 2     * (((( * (1 - )) / n)

= 2.576* (((0.17*0.83) /250 )

E = 0.061