n = 20, the number of questions
p = 1/5 = 0.2, the probability of making a correct guess
q = 1 - p = 0.8, the probability of making an incorrect guess.
Expected successĀ = 60% or 6 of 10.
From the binomialĀ distribution,
P(6 of 10) =Ā āāCā pā¶qā“
Ā Ā Ā Ā Ā Ā Ā Ā Ā = 210*0.2ā¶*0.8ā“ = 0.0055
Answer: 0.0055
