8.48 Effect of the sample sizes. Suppose that p₁ = 0.4, n₁ = 100, p₂ = 0.5, n₂ = 120.

1. (a) Find the mean and the standard deviation of the sampling distribution of p₁ − p₂.

2. (b) The sample sizes here are four times as large as those in the previous exercise while the population proportions are the same. Compare the results for this exercise with those that you found in the previous exercise. What is the effect of multiplying the sample sizes by 4?