Chapter 10.3, Problem 2P

Statistical Literacy Consider a hypothesis test of difference of proportions for two independent populations. Suppose random samples produce $r_1$ successes out of $n_l$ trials for the first population and $r_2$ successes out of $n_2$ trials for the second population. What is the best pooled estimate $\bar{p}$ for the population probability of success using $H_0:p_1=p_2$?