Question 870230
p(correct) = .25,  n = 20
P(x = 4) = binompdf(20, .25, 4)= .1897
P(x = 3) = P(x = 3) = binompdf(20, .25, 3) = .1339
p(x > 8) = 1 - P(x = 7) = binomcdf(20, .25, 7) = .0409
P( 4≤ x ≤ 6) =  .7858 - .7749 = .0111
P( x ≥ 4 ) = 1 - binomcdf(20, .25, 3)= .7748
P(x ≤ 6) = binomcdf(20, .25, 6)= .7858