For a given sample proportion p, show that a value o for which the test statistic z = (p-)/(1-0)/n] takes some fixed value zo (such as 1.96) is a solution to the equation (1+z/n) + (-2p-2/n)o+p = 0. Hence, using the formula x = [-b (b-4ac)]/2a for solving the quadratic equa- tion ax + bx+c = 0, obtain the limits for the 95% confidence interval in Section 1.3.4 for the probability of success when a clinical trial has nine successes in 10 trials.