CHAPTER 11

Confidence Intervals and Introduction to Inference

1. 
   

        A   recent  poll    estimated   that    about   18% of  the U.S.    population  live    in  a   multigenerational   family

   
   

   household. The 95% confidence interval is from 15% to 21%. Which of the following correctly
   interprets the meaning of “95% confident”?
   (A) If many samples were taken, about 95% of the confidence intervals would contain the actual
   proportion of the U.S. population that live in a multigenerational family household.
   (B) If many samples were taken, about 95% of the samples would have between 15% and 21% of
   those sampled living in a multigenerational family household.
   (C) There is a 95% probability that any particular sample would have between 15% and 21% of
   those sampled living in a multigenerational family household.
   (D) Ninety-five percent of people sampled live in a multigenerational family household.
   (E) Between 15% and 21% of the U.S. population live in a multigenerational family household
   about 95% of the time.

   
   


2. A quality control manager for a cookie company selected a random sample of 20 chocolate chip
   cookies from all chocolate chip cookies produced on a particular day. She counted the number of
   chocolate chips in each cookie; the average number of chips was 26.2, and the standard deviation
   was 2.43. The distribution of number of chocolate chips was reasonably symmetric and mound-
   shaped. The 92% confidence interval for the mean number of chips for all cookies produced that day
   is

(A)         

(B)

(C)

(D)