each question has 1 correct answers...and their are 5 possible answers
probability of getting 1st question correct is 1/5
probability of getting 2nd question correct is 1/5
probability of getting 3rd question correct is 1/5
and since all of these events are independent, to find the probability of getting all 3 right, we must multiply
1/5 * 1/5 * 1/5 = 1 / 125 <==