Hey, this is Presh Talwalkar. Surveys have found that eighty percent of people get this problem wrong. While you are thinking about it I am going to present a similar problem. Give these problems a try and when you’re ready keep watching the video for the solution. Many people think that the answer to the first problem is C) Cannot Be Determined. However, we need to work through the logical possibilities. While we do not know Bob’s marital status we should work out each case to see if the condition is met. One case is that Bob is married. In that case, he is a married person whose looking at Charlie, who is unmarried. So if Bob is married The condition that a married person is looking at an unmarried person is true. What would happen if Bob is not married? In that case, Alice, whose married, is looking at Bob, whose unmarried. So in this case too, it would be true that a married person is looking at an unmarried person. So the correct answer choice is A) Yes Although we don’t know which married person is looking at an unmarried person We know that some married person is looking at an unmarried person. Now let’s tackle the next problem! Imagine that we draw the three socks in order. Now, it could be the case that the first two socks you pull are both black or they’re both white. In that case, you would already have a matching pair of socks before you even pull the third sock. Now what would happen if that’s not the case? Well, then the first two socks would have to be different colors. You would have to have one white and one black sock. Then, when you pull the third sock, It would have to be either a white sock –matching the white sock you already have– or a black sock–matching the black sock you already have. The third sock must match one of the socks you already have. Therefor, in either case, you will always be holding a matching pair of socks. Did you figure out these problems? Thanks for watching this video! Please subscribe to my channel. I make videos on math and game theory. You can catch me on my blog, MindYourDecisions which you can follow on Facebook, Google+, Patreon. You can catch me on social media @preshtalwalkar And if you liked this video, please check out my books. There are links in the video description.