Thanks to Brian Galebach who created and sent me this problem! You arrive at a park where geysers A, B, and C erupt at intervals of precisely 2, 4, and 6 hours, respectively. Each started erupting independently at a random time in history, unknown to you. What are the probabilities that each geyser (A, B, and C) will be the first to erupt after your arrival? I also received an email this problem was asked during an interview for Amazon. David Weaver created a simulation on Khan Academy where you can see the probabilities after many trials https://www.khanacademy.org/computer-programming/three-geysers-problem/6383430987464704 My blog post for this video https://wp.me/p6aMk-7Y1 Source: Brian Galebach created the problem and gave permission for me to post it in a video. It was previously shared on Oliver Roeder's Riddler column on 538: https://fivethirtyeight.com/features/which-geyser-gushes-first/ . https://fivethirtyeight.com/features/how-long-will-your-smartphone-distract-you-from-family-dinner/#solution This is a creative approach, but I personally felt it was hard to visualize and calculate the volumes. But it is neat: http://advancedmathyoungstudents.com/blog/2015/12/24/3d-visualization-geometric-probability-and-538s-riddler-2/ If you like my videos, you can support me at Patreon: https://www.patreon.com/mindyourdecisions Connect on social media. I update each site when I have a new video or blog post, so you can follow me on whichever method is most convenient for you. My Blog: https://mindyourdecisions.com/blog/ Twitter: https://twitter.com/preshtalwalkar Facebook: https://www.facebook.com/pages/Mind-Your-Decisions/168446714965 Google+: https://plus.google.com/108336608566588374147/posts Pinterest: https://www.pinterest.com/preshtalwalkar/ Tumblr: https://preshtalwalkar.tumblr.com/ Instagram: https://instagram.com/preshtalwalkar/ Patreon: https://www.patreon.com/mindyourdecisions Newsletter (sent only for big news, like a new book release): http://eepurl.com/KvS0r If you buy from the links below I may receive a commission for sales. This has no effect on the price for you. My Books "The Joy of Game Theory" shows how you can use math to out-think your competition. (rated 3.9/5 stars on 32 reviews) http://amzn.to/1uQvA20 "The Irrationality Illusion: How To Make Smart Decisions And Overcome Bias" is a handbook that explains the many ways we are biased about decision-making and offers techniques to make smart decisions. (rated 4.6/5 stars on 3 reviews) http://amzn.to/1o3FaAg "Math Puzzles Volume 1" features classic brain teasers and riddles with complete solutions for problems in counting, geometry, probability, and game theory. Volume 1 is rated 4.4/5 stars on 13 reviews. http://amzn.to/1GhUUSH "Math Puzzles Volume 2" is a sequel book with more great problems. (rated 4.3/5 stars on 4 reviews) http://amzn.to/1NKbyCs "Math Puzzles Volume 3" is the third in the series. (rated 3.8/5 stars on 5 reviews) http://amzn.to/1NKbGlp "40 Paradoxes in Logic, Probability, and Game Theory" contains thought-provoking and counter-intuitive results. (rated 4.3/5 stars on 12 reviews) http://amzn.to/1LOCI4U "The Best Mental Math Tricks" teaches how you can look like a math genius by solving problems in your head (rated 4.7/5 stars on 4 reviews) http://amzn.to/18maAdo "Multiply Numbers By Drawing Lines" This book is a reference guide for my video that has over 1 million views on a geometric method to multiply numbers. (rated 5/5 stars on 3 reviews) http://amzn.to/XRm7M4