plot ((x/(x+y)) + ((1.96^2/2)/(2*(x+y))) - (1.96/2)*sqrt((((x/(x+y))*(1-(x/(x+y)))) + (1.96^2/2)/(4*(x+y)))/(x+y)))/(1 + (1.96^2/2)/(x+y)), x=0..10, y=0..10