Question

The Gallup Poll asked 500 U.S. adults whether they believed that people should pay sales tax on items purchased over the Internet. Of these, 180 said they supported such a tax. Does the survey provide convincing evidence that less than 39% of U.S. adults favor an Internet sales tax? Use p-value method and 0.01 significance level.

Answer 1

H0: p = 0.39

Ha: p < 0.39

Sample proportion = 180 / 500 = 0.36

Test statistics

z = ( - p ) / sqrt [ p ( 1 - p) / n ]

= ( 0.36 - 0.39) / sqrt [ 0.39 ( 1 - 0.39) / 500 ]

= -1.375

p-value = P(Z < z)

= P(Z < -1.375 )

= 0.0846

Since p-value > 0.01 level, fail to reject H0.

We conclude that we do not have sufficient evidence to support the claim that less than 39% of

U.S. adults favor an Internet sales tax.