Elderly patients who had suffered hip fractures were randomly assigned to receive either a placebo (n = 1,062) or zolendronic acid (n = 1,065) in a double-blind clinical trial. During the trial 139 placebo patients and 92 zolendronic acid patients had new fractures. Let p1 and p2 represent the probabilities of fracture on placebo and zolendronic acid, respectively. Construct a 95% confidence interval for (p1 - p2).