9.1

25.

  1. .181

  2. 2306 * .181 (1-.181) = 341.84 >10 Sample is less than 5% of population

  3. Lower Bound = .168 Upper Bound = .194

  4. We are 90& confident that the population proportion of adults who have given blood in the last two years is between .168 and .194.

26.

  1. 496/1153 = .4302

  2. 1153 * .4302 (1-.4302) = 282.62 >10 , sample is less than 5% of population

  3. Lower Bound = .0223 Upper Bound = .03485

  4. We are 95% confident that the proportion of workers and retirees aged 25 and older that have less than $10,000 in savings is in between .0223 and .0349.

27.

  1. .519

  2. 250.39 > 10, sample is less than 5 % of the population

  3. Lower bound = .488 Upper bound = .550

d)It is possible that the proportion is more than 60%, because it is not guaranteed that the true prpoportion is captured in the conifedence interval, however it is unlikely because it is not in the interval.

  1. Lower bound = .45 Upper Bound = .512

28.

  1. 768/1024 = .75

  2. 192 > 10, sample is les than 5% of population

  3. Lower Bound = .02469 Upper Bound = .04499

  4. It is possible, but extremely unlikely because we are 99% sure the proportion is in between .02469 and .04499

  5. Lower Bound = .03146 Upper Bound = .03822

29.

  1. .111 Lower Bound = .071 Upper Bound = .151

  2. Lower Bound = .058 Upper Bound = .164

  3. Increasing the confidence level increases the margin of error.