Question

A medical researcher says that less than 25?% of adults in a certain country are smokers. In a random sample of 250 adults from that? country, 18?% say that they are smokers. At =0.05, is there enough evidence to support the researcher's claim?

1. Stat the null and alternative hypothesis

2. What is the P-Value?

3. What is the Test Statistic?

4. State the conclusion in Text

Answer 1

(1) Claim is that  less than 25% of adults in a certain country are smokers

Null hypothesis Ho: p = 0.25

Alternate hypothesis H1:- p < 0.25 (claim)

(2) population proportion po = 0.25 and sample proportion = 0.18

sample size n = 250

p value = 0.0052 [From z table for z = -2.56]

(3) test statistic is z = -2.56 (calculated in previous part)

(4) we can see that p value(0.0052) < significance level 0.05, rejecting the null hypothesis

Conclusion:_ there is sufficient evidence to support the claim that less than 25% of adults in a certain country are smokers