Question

if you make guesses for four multiple-choice test questions (each with five possible answers), what is the probability of getting at least one correct?

Answer 1

prob(right) = 1/5
prob(wrong) = 4/5

prob(at least one correct)
----> exclude the case of all wrong

prob(all wrong ) = (4/5)^4

prob(at least one right ) = 1 - (4/5)^4
= 369/625