Three friends Alan, Roger and Peter attempt to answer a question on an exam. Alan randomly guesses the answer, giving him a 1/5 probability of guessing correctly. Roger cheats by looking at the paper of the student in front of him, giving him a 2/3 probability of answering correctly. And Peter dutifully performs the calculations, then marks the answer, giving him a 5/6 probability of a correct answer. What is the probability that the question is answered correctly, but not via cheating?
Correct answer: A
Explanation
Prob(Alan) = 1/5
Prob(Roger) without cheating = 2/3-1 = 1/3
Prob(Peter) = 5/6
Total Probability = 1/5*1/3*/5/6 = 1/18
Answer is A
Loading…
Searched on YouTube by reporting category, not by question text. Open this search on YouTube →
AQuA-RAT items are crowdsourced algebra problems, not ACT questions. They carry five answer choices in the pre-2025 ACT Mathematics style and no ACT reporting category. Useful for drilling Preparing for Higher Math content; not a substitute for a real form.