The width of a confidence interval estimate for a proportion will be:

The width of a confidence interval estimate for a proportion will be:
 a. narrower for 99 confidence than for 95 confidence
  b. wider for a sample size of 100 than for a sample size of 50
  c. narrower for 90 confidence than for 95 confidence
  d. narrower when the sample proportion if 0.50 than when the sample proportion is 0.20
  e. none of these

Q. 2

Given that Z is a standard normal random variable, P(Z > 1.58) is:
 a. 0.4429
  b. 0.0571
  c. 0.9429
  d. 0.5571
  e. 0.6910

Q. 3

After calculating the sample size needed to estimate a population proportion to within 0.04, your statistics professor told you the maximum allowable error must be reduced to just .01 . If the original calculation led to a sample size of 800, the sample size will now have to be:
 a. 800
  b. 3200
  c. 12,800
  d. 6400
  e. 1600

Q. 4

Given that Z is a standard normal random variable, what is the value z if the area to the right of z is 0.9066?
 a. 1.66
  b. 1.32
  c. 0.66
  d. 0.66
  e. 1.02

Q. 5

From a sample of 400 items, 14 are found to be defective. The point estimate of the population proportion defective will be:
 a. 14
  b. 0.035
  c. 28.57
  d. 0.05
  e. 0.26

Q. 6

Given that Z is a standard normal random variable, what is the value z if the area to the right of z is 0.1949?
 a. 0.75
  b. 0.51
  c. 0.86
  d. 0.68
  e. 0.55

Q. 7

The lower limit of a confidence interval at the 95 level of confidence for the population proportion if a sample of size 200 had 40 successes is:
 a. 0.2554
  b. 0.1446
  c. 0.2465
  d. 0.1535
  e. 0.3390

Q. 8

If the random variable X is normally distributed with a mean of 75 and a standard deviation of 8, then P(X >= 75) is:
 a. 0.125
  b. 0.500
  c. 0.625
  d. 0.975
  e. 0.250