Question

Many traffic accidents are blamed on motorists who are distracted by cell phone use while driving. In a 1999 survey, 30% of adults said that they make phone calls sometimes or frequently while driving alone. A recent random sample of 500 adults showed that 165 of them make phone calls sometimes or frequently while driving alone. At the 1% level of significance, can you conclude that the current proportion of adults who make such phone calls exceeds .3? Identify the proper Test or Confidence interval: Complete the Test or Confidence Interval.

Answer 1

The null and alternate hypothesis are:

H0:

Ha:

We know that 99% CI for true proportion is given by:

Since this interval contains the value 0.3, so at 1% level of significance, we do not have sufficient evidence to reject H0.

Thus we cannot conclude that the current proportion of adults exceeds 0.3.