Question

On a multiple choice test, each question has five possible answers. a student does not know the answers to two questions, so he guesses. what is the probability that the student will get them both wrong?

Answer 1

The probability that he gets one of them wrong is 4/5 for there will only be one correct answer for every 4 wrong ones.

Now, to work out the probability that he gets BOTH wrong, we have to multiply the probability that he gets each of them wrong with each other. So:

4/5 x 4/5 = 16/25

So the probability that he gets BOTH wrong is 16/25 or 64% !