9.3 Calculate the sample size you would need for each of the following situations (using the basic formulas provided in this chapter): a. A sample survey that provides a margin of error of + 2 percentage points. b. A sample of cars on a stretch of highway that results in a mean estimate of the speed of the traffic that has a margin of error + 2 miles per hour. (Hint: Assume the range of speeds is between 40 and 80 miles per hour.) c. A comparison of hourly wages between men and women in which you would have enough power to detect even a small difference (defined by Cohen as an effect size of 0.20)