Difference between population proportions is atom bomb equal

Question

Assignment:

Testing for Constant Difference To test the null hypothesis that the difference between two population proportions is equal to a nonzero constant c, use the test statistics

z= (ˆp₁ -ˆP₂)-c/√ˆp₁ˆq₁/n₁ +ˆp₂ˆq₂/n₂

As long as n1 and n2 are both large, the sampling distribution of the test statistic z will be approximately the standard normal distribution. Refer to Exercise 27 and use a 0.01 significance level to test the claim that the rate of thyroid disease among female atom bomb survivors is equal to 15 percentage points more than that for male atom bomb survivors.