Determine the overall sample size required so that a 95% lower bound confidence interval for the difference of two proportions will have a margin of error of ???????? = 0.035 when

(a) ????̇ ???? = 0.50 and ????̇ ???? = 0.75.

(b) ????̇ ???? = 0.45 and ????̇ ???? = 0.50.

(c) ????̇ ???? = 0.90 and ????̇ ???? = 0.50.

(d) no prior knowledge of the proportions is available.