Question 914294
p = .75,  n = 25
a) 18/25 = .72, z(0.72) = (0.72-0.75)/sqrt[0.75*0.25/25) 
P (x >18) = normalcdf(z, 100)
...........
b) zL = (.48-.75)/sqrt[0.75*0.25/25), zH = (.6 - .75)/sqrt[0.75*0.25/25) 
P( 12 < x < 15) = normalcdf(zL,zH)
..........
mean = {{{.75*25}}}, sd = {{{sqrt(.75*.25*25)}}}