1.We can use the normal distribution to make confidence interval estimates for the population proportion, p, when: a. n(1 - p) ≥ 5 b. p has a normal distribution. c. Both np ≥ 5 and n(1 - p) ≥ 5. d. np ≥ 5 2.The margin of error in an interval estimate of the population mean is a function of all of the following except: a. sample mean. b. variability of the population. c. sample size. d. level of significance