 This is an example on how to calculate probabilities, which could be used to build a probability distribution. There are multiple choice questions on the test or quiz that each have three possible answers, only one of which of course is correct. Assume you guessed the answers to five such questions. So let's see denote a correct answer and w denote a wrong answer. As the five questions or trials find the probability that only if you were to randomly guess now that only the fifth answer would be correct. Find the probability that the first four would be wrong and the fifth one would be correct. Now, these are independent trials. I do have independent trials here. Because whatever I pick on the first answer does not affect the probability of whatever I pick for the second answer in the third, fourth and fifth. The probabilities are fixed all across the board here. So find probability the first one's wrong. Times probability second one's wrong. Times probability third one's wrong. Times probability of fourth one's wrong. Times probability the fifth one's correct. So for each question you have three choices to pick from. How many are wrong? How many are correct? Well, there's two ways to get the question wrong only one way to get it right. So two thirds probability of getting the second question wrong two thirds third question wrong two thirds fourth question wrong two thirds fifth question wrong or right correct. Probability getting the fifth question correct is one third. So two times two times two times two is going to give you 16 and three times three times three times three times three gives you 243. And if I want to give this as an answer to four decimal places it's point 0658. Now find a probability of getting one correct answer in any order. So there are many ways for this to happen. The correct answer could be the first question. The correct answer could happen on the second question. The correct answer could happen on the third question could happen on the fifth question. Or it could even happen on the fourth question. Regardless, there's five different ways. That you can get exactly one correct answer. So what you do is you take the probability from part a, which was one of the probabilities of getting a correct answer the one where you got the correct answer in the fifth position. And you multiply it by five. I'm going to multiply the fraction by five because that gives me a more accurate answer. So five times 16 over 243 is point. 3292. That's the probability of getting one correct answer in any order. Now we can actually use this information or this example to find the values for a binomial probability experiment using the binomial formula, and you will learn more about that as well in the near future.