Answer to Question #198536 in Statistics and Probability for Matthew Kayton

Question

Construct a 90% confidence interval for the true proportion of all employees of Big Star Ltd who believe that they deserve a salary increase, given that 80 out of a sample of 130 employees said that they believe that they deserve a salary increase.

Answer 1

We have given that,

$n = 130$

$p = \dfrac{80}{130} = 0.615$

We know,

$CI = p \pm z \sqrt{\dfrac{p(1-p)}{n}}$

$CI = 0.615 \pm 1.645\sqrt{\dfrac{0.615 \times 0.385}{130}}$

$CI = 0.615 \pm 0.0070$