Michael takes a multiple-choice test with 5 answer choices for each question. If he randomly answers every question what is his expected score?

Question

inkyvoyd · Answer

20%

inkyvoyd · Answer

as number of questions approaches infinity.

anonymous · Answer

really depends on how many questions on the test right?

inkyvoyd · Answer

yes, in that case, use nCr ((p)^r)(1-p)^(n-r)

anonymous · Answer

oh right, expected "score" not expected number of correct answers.

inkyvoyd · Answer

n= questions, r=number of correct, p=probability of correct.

anonymous · Answer

inkyvoyd is right, expected "score" is 20% 
expected number of correct answer is .2 n if n is the number of questions answered