You randomly guess the answers to two questions on a multiple-choice test. Each question has three choices: A, B, and C. What is the probability that the answer is correct?
The answer for one of them, or the answer for two of them. For both answers to be correct, there is a 1 in 9 chance because 1/3*1/3 = 1/9.
But if you want to find the probability that one answer is right and the other is wrong is 1/3*2/3 which is 2/9. But, you have to multiply that by two because you can have the first right and the second wrong or the second right and the first wrong, so it is actually 4/9. Both answers right: 1/9, one answer right one answer wrong:4/9, Both right or one right one wrong:5/9