You Want to Estimate the Difference in Grade Point Averages

Essay

You want to estimate the difference in grade point averages between two groups of students, accurate to within 0.20 of a grade point, with confidence equal to 0.95. If the standard deviation of the grade point measurements is approximately equal to 0.5, how many students must be included in each group? (Assume that the groups will be of equal size.) Justify your conclusion.