Answer:
0.22514
Step-by-step explanation:
Given :
1 answer from 4 options
p = 1/4 = 0.25 ; q = 1 - 0.25 = 0.75
n = 20
P(x ≤ 3) = p(x =0) +p(x=1) + p(x=2) +p(x=3)
P(x = x) = nCr * p^x * q^(n-r)
p(x =0) = 20C0 * 0.25^0 * 0.75^20 = 0.00317
p(x =1) = 20C1 * 0.25^1 * 0.75^19 = 0.02114
p(x =2) = 20C2 * 0.25^2 * 0.75^18 = 0.06694
p(x =3) = 20C3 * 0.25^3 * 0.75^17 = 0.13389
P(x ≤ 3) = 0.00317+0.02114+0.06694+0.13389 = 0.22514
