Hi
p(correct) = 1/5 = .20, n = 4
TI syntax for P(x-value) is binompdf(n, p, x-value).
1.P(x = 0) = binompdf(4, .2, 0) = .4096 0r 40.96%
2. P(x ≤ 2)= binomcdf(4, .2, 2) = .9728 0r 97.28%
TI syntax is binomcdf(n, p, largest x-value) for binomial ≤ cumulative probability