Solve this puzzle to get into Oxford ?!

mind your decisions i'm presh tallwalker a version of this problem was an interview question for admission to oxford university a prize is placed under one of five objects shilpa is privately told the shape of the object and colin is privately told the color of the object shilpa and colin are mathematicians who use perfect logical reasoning and the initial setup is common knowledge the host asks do either of you know where the prize is both of them are silent the hosts then ask do you know now again they are both silent finally the host asks do you know now chopa and colin simultaneously say yes the question is where is the prize i think the puzzle author professor joel david hampkins and i saw this problem via alex belos's puzzle column on the guardian pause the video if you'd like to give this problem a try and when you're ready keep watching to learn how to solve this problem [Music] so how can we solve this problem shilpa was privately told the shape of the object if she was told triangle she would know it's either the green triangle or the blue triangle if instead she was told circle then she would have known it was the yellow circle or the green circle if she was told square then she would have known it was the blue square similarly colin was privately told the color of the object if he was told green he would know it's either the green triangle or the green circle if he was told blue he would know it's either the blue square or the blue triangle if he was told yellow then he would have known it was the yellow circle so let's analyze the first question the host asked do you know where the prize is both shilpa and colin are silent so what does that mean for each person let's analyze shilpa if shilpa had been told square she would have known the price is under the blue square she didn't know this she was silent so we can eliminate that shilpa was initially told square now similarly if colin had been told the color was yellow initially then he would have known it's the yellow circle but colin was silent so we can eliminate this he was not told yellow initially now shilpa has perfect logical reasoning so she knows that since colin was silent he was not told yellow initially so shilpa can eliminate the yellow circle as one of her options similarly colin knows that shilpa was not told square initially so he can then eliminate the blue square from his options so now we go to the second stage of reasoning now the host asked do you know now once again they are both silent so we can repeat this type of logical reasoning at this stage if shilpa had been told circle initially the only option would be the green circle by this stage she would have known where the prize was she was again silent so this is not what she was told initially similarly if colin had been told blue initially then by this stage he would be able to figure out the prize is under the blue triangle but again he was silent so we could eliminate this he was not told blue initially so we now go into the final stage of reasoning the host asks do you know now by this point shilpa realizes that colin must have been told green initially and colin realizes that shilpa must have been told triangle initially putting that together with their initial information they both realize yes it must be the green triangle so they both exclaimed yes i know where the prize is and it's under the green triangle and that's the answer what a fun logic puzzle thanks for making us one of the best communities on youtube see you next episode of mind your decisions where we solve the world's problems one video at a time you

Channel: MindYourDecisions

Views: 6,807,799

Keywords: mathematics, math, maths, riddle, brain teaser, puzzle, math puzzle

Id: PVFwUGE6mBU

Length: 5min 29sec (329 seconds)

Published: Tue Sep 21 2021