Answers to Assign. 19-3: Ch. 19 Practice 1) Condition Check Random Sample We have to assume this n < 10% of N We know 1500 is <10% of all Americans np ≥ 10 and n(1 – p) ≥ 10 (we have to use p instead) 1500(.68) ≥ 10 1020 ≥ 10 1500(.32) ≥ 10 480 ≥ 10 We are 97% confident that between 65.4% and 70.6% of all Americans support campaign finance reform. ^

2) Condition Check Random Sample We have to assume this n < 10% of N We know 200 IS < 10% of all HS seniors np ≥ 10 and n(1 – p) ≥ 10 (we have to use p instead) 200(.74) ≥ 10 148 ≥ 10 200(.26) ≥ 10 52 ≥ 10 We are 99% confident that between 66.0% and 82.0% of all high school seniors feel that their high school experience has been valuable. ^ 2

3) Yes, the interval we calculated supports his belief since 70% falls within it. 4) Condition Check Random Sample Assume n < 10% of N We know 1039 is <10% of all adults np ≥ 10 and n(1 – p) ≥ 10 (we have to use p instead) 1039(.39) ≥ 10 405 ≥ 10 1039(.61) ≥ 10 634 ≥ 10 We are 95% confident that the true proportion of adults who plan to take more vacations this year is between 36.0% and 41.9%. ^ 3

5) 6)