9.1

25.

  1. type answer here. .1808

  2. type answer here. np(1-p) =34.8 >10 and the sample is less than 5 % of the population

  3. type answer here. .1676, .1939

  4. type answer here. We are 90 % confident that the proportion of adults age 18 and over who have donated blood in the past 2 years is between .1676 and .1939.

26.

  1. type answer here. .4301
  2. type answer here. np(1-p)=282.616 >10, and the sample size is less than 5 % of the population
  3. type answer here. .4015, .4586
  4. type answer here. We are 95 % confident that the proportion of workers and retirees 25 years of age and older that had less than 10000 in savings is between .4015 and .4586.

27.

  1. type answer here. .0519
  2. type answer here. np(1-p) = 250.39 > 10 and the sample is less than 5 % of the population
  3. type answer here. 0.488, 0.550
  4. type answer here. Yes, it is possible that the true proportion is not captured in the confidence interval.

  5. type answer here. 0.450, 0.512 28.

  6. type answer here. .75
  7. type answer here. np (1-p) =144 >, and the sample is less than 5 % of the population
  8. type answer here. .1585, .2030
  9. type answer here. It is possible for the proportion of adults to be below 70 %, but it is very slim because we have a 99 % confidence interval

  10. type answer here. .2150, .2849 29.

  11. type answer here. 0.071, 0.151
  12. type answer here. 0.058, 0.164

  13. type answer here.

As the level of confidence increases, the margin of error increases.