Suppose the student guesses the answers, we shall consider this a binomial probability problem of success. This implies that getting a question right is p=1/5. The number of questions is n=20 questions. The mean of binomial distribution is mean=n*p= 20*1/5=4
b] The standard deviation of a binomial distribution is given by: σ=√(n*p*(1-p)) =√(20*0.2*0.8) =1.79~1.8
