9.1

25.

  1. 0.181

  2. 341.8>10, thus it is less than 5%

  3. lower:0.488, upper:0.194

  4. 90% confident that the proportion of americans over 18yrs old that have donated blood is between 0.168 and 0.194

26.

  1. 0.430

  2. 282.6>10, thus it is less than 5%

  3. upper: 0.495, lower:0.401

  4. 95% confident that the proportion is between 0.401 and 0.495

27.

  1. 0.519

  2. 250.39>10 thus it is less than 5%

  3. Lower:0.488, Upper:0.550

  4. Yes, but it is unlikely.

  5. lower:0.450, upper:0.512

28.

  1. 0.75

  2. 192>10, thus it is less than 5%

  3. lower:0.715, Upper:0.785

  4. 99% confident that the proportion is in between 0.715 and 0.785 29.

  5. lower: 0.071, upper:0.151

  6. lower: 0.058, upper:0.164

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