In the context of a hypothesis test for two proportions, which of the following statements about the pooled sample proportion,

p⎯⎯ , is/are true? I. It estimates the common value of p1and p2 under the assumption of equal proportions. II. It is obtained by averaging the two sample proportions p1ˆ and p2ˆ . III. It is equal to the proportion of successes in both samples combined.