Let n1 =100​, x1=60 ​, n2 =100​, and x2=80 . Complete part​ (b) below.

Question

Calculate the test​ statistic,

ZSTAT​,

based on the difference

p1−p2.

The test​ statistic,

ZSTAT​,

is

negative 3.09−3.09.

​(Type an integer or a decimal. Round to two decimal places as​ needed.)

Calculate the​ p-value.

The​ p-value is

0.0020.002.

​(Type an integer or a decimal. Round to three decimal places as​ needed.)

b. Construct a 90​% confidence interval estimate of the difference between the two population proportions.

enter your response here≤π1−π2≤enter your response here

Answer 1

CI = (phat1 - phat2) +/- z-critical * sqrt(p-pooled(1/n1 + 1/n2)

z-critical for 90% CI is 1.645

phat1 = x1/n1

phat2 = x2/n2

p-pooled = (x1 + x2)/(n1 + n2)

plug in numbers to compute above 3 values. Then plug those numbers plus given z-critical into formula for CI.