Question

A medical researcher says that less than 25% of American adults are smokers. In a random sample of 200 adults, 28.5% say that they are smokers. At a=0.01, do you have enough evidence to reject the researcher’s claim?

a. State the null and alternative hypotheses.

b. State the Type I and Type II errors.

c. Find the critical value. Do you have enough evidence to reject the manufacturer’s claim?

d. Construct a 95% confidence interval for the difference of population means.

Answer 1

The medical researcher's expectation is wrong. There is enough statistical evidence to prove that 25% or more are smokers in the university.