Question

6. According to Scarborough Re-search, more than 85% of working adults commute by car. Of all U.S. cities, Washington, D.C., and New York City have the longest commute times. A sample of 30 commuters in the Washington, D.C., area yielded an average commute time, in minutes of ?̅ = 27.97 minutes and s = 10.04 minutes. We want to test the hypothesis that the average driver commutes more than 25 minutes at the 5% significance level.

1. State the null and alternative hypotheses.

2. What is the value for the test statistic, t0?

3. What is critical-value?

4. Does the study provide good evidence that the average driver commutes more than 25

   minutes?

Answer 1

Solution :

The null and alternative hypothesis is ,

H0 :   = 25

Ha : > 25

Test statistic (t0) =

= ( - ) / s / n

= (27.97 - 25) / 10.04 / 30

t0 = 1.62

= 0.05

df = n - 1 = 29

Critical-value t,df = 1.699

P-value = 0.0580

P-value >

Fail to reject the null hypothesis .

There is insufficient evidence that the average driver commutes more than 25 minutes