Children and Environmental Tobacco Smoke at Home. Use the following information for Exercises 41–44. The Environmental Protection Agency reported that 11% of children age 6 and under were exposed to environmental tobacco smoke (ETS) at home on a regular basis (at least four times per week).15 A random sample of 100 children age 6 and under showed that 6% of these children had been exposed to ETS at home on a regular basis.

Question 9.309

43. Refer to your work in Exercise 41.

  1. Test at level of significance whether the population proportion of children age 6 and under exposed to ETS at home on a regular basis has decreased.
  2. How do you explain the different conclusions you got in the two hypothesis tests above?
  3. Evaluate the strength of evidence against the null hypothesis.

9.5.43

(a) Since the , we reject . There is evidence that the population proportion of children age 6 and under exposed to environmental tobacco smoke at home on a regular basis is less than 0.11. (b) The difference is because we changed the value of and not because we used different methods for the two different hypothesis tests. (c) Since , there is mild evidence against the null hypothesis that the population proportion of children age 6 and under exposed to environmental tobacco smoke at home on a regular basis is greater than or equal to 0.11.