9.1

25.

  1. p hat = .181

  2. 341.84 > 10 and the sample is less than 5% of the population

  3. Lower Bound: 0.168, Upper Bound: 0.194

  4. We are 90% confident the population proporiton of 18 year olds and older Americans who domated blood in the past 2 years is between 0.168 and 0.194

26.

  1. p hat = .430

  2. 282.6003 > 10 and the sample is less than 5% of the population

  3. Lower bound: - 0.401, Upper bound: 0.035

  4. We are 95% confident the population proportion of 25 year olds and older who had less than $10,000 in savings is between -.401 and .035

27.

  1. p hat = 0.519

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

  3. Lower bound: 0.488, Upper bound: 0.550

  4. It is possible, becuase it is possible that the true proportion is not captured in the confidence interval. But it isnot likely because 0.6 is outside the confidence interval.

  5. Lower bound: 1 - 0.550 = 0.450, Upper bound: 1 - .488 = 0.512

28.

  1. p hat = .75

  2. 192 > 10 and sample is less than 5% of the population

  3. Lower bound: -0.025, Upper bound: 0.045

  4. This is not very likely because .70 is pretty far outside of the confidence interval.

  5. Lower bound: 1 - (-.25) = 1.025, Upper bound: 1-.045 = .955

29.

  1. p hat = .111, Lower bound: .071, Upper bound: .151

  2. Lower bound: .058, Upper bound: .164

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