Confidence Interval (C.I.) on difference between two proportions Treadmill p1 0.362162 Service contract sold q1 0.637838 Service contract NOT sold n1 185 Service contract 67 zc 1.96 sigma(p1) 0.069259 0.2929030558 <= Exercise Bike p2 0.447154 q2 0.552846 n2 123 95% Confidence Level p1 Sigma(p1-p2) Proportion difference Confidence Interval <= 0.111883 -0.084992 Min -0.196875 0.431421 max 0.02689 Service contract 55 zc 1.96 sigma(p2) 0.087869 0.3592857707 <= Service contract sold Service contract NOT sold p2 <= 0.535023