A multiplechoice test contains n questions If answers are ra

A multiple-choice test contains n questions. If answers are randomly selected, the correct answer will be selected with probability p. What is the probability that X, the number of questions that the student answers correctly, equals x?

Solution

This one follows the binomial probability distribution. Thusm

P(X=x) = nCx p^x (1-p)^x    [ANSWER]

where nCx = n!/(x!(n-x)!).