# Brain Teasers **URL:** \ **Category:** The Game Room\ **Created:** [July 26, 2010, 4:05pm UTC](https://boards.straightdope.com/t/brain-teasers/548065 "2010-07-26T16:05:31Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![armedmonkey](https://avatars.discourse-cdn.com/v4/letter/a/d6d6ee/32.png) [@armedmonkey](https://boards.straightdope.com/u/armedmonkey)\ **Post date:** [July 27, 2010, 12:36am UTC](https://boards.straightdope.com/t/brain-teasers/548065/21 "2010-07-27T00:36:04Z")
deleted ---
**Author:** ![Superhal](https://avatars.discourse-cdn.com/v4/letter/s/b4bc9f/32.png) [@Superhal](https://boards.straightdope.com/u/Superhal)\ **Post date:** [July 27, 2010, 1:42am UTC](https://boards.straightdope.com/t/brain-teasers/548065/22 "2010-07-27T01:42:04Z")
> [@KennerTheGreat](#): > > 1. After a power surge disrupted all the electronic devices in Brian’s house, he had to go over to Amy’s to find out what time it was. After she told him, Brian walked home and set all of his clocks. Even though Brian didn’t know how long it had taken him to get home, he was able to set his clocks to exactly the right time. How? > > 2. I was about to leave on a morning flight to Paris when I realized I left my briefcase in my office. I rushed back to get it, but the night watchman said “Do not get on that plane! I had a dream last night that it’s going to crash!” Not wanting to tempt fate, I stayed home. Sure enough, the plane crashed. That evening, I thanked the man for saving my life, then I fired him. Why? > > 3. Seven men were leaving church together when it started to rain. The six who ran got wet, the seventh, who didn’t stayed dry. How? > > 4. One day, Tom found himself trapped in a room with two doors. Behind the first door was a room made of thick glass that would magnify the sun’s heat to fry whoever went in. Behind the second door was a fire-breathing dragon that would do the same. How did Tom escape unscathed? > > 5. Malcolm and Joanna competed in a strange horse race. Whoever’s horse reached the finish line _last_ would be the winner. After waiting a few hours for them to go a few feet, I walked out, called them off their horses, and told them something. Immediately, Malcolm and Joanna jumped up on the horses and rode them as fast as they could to the finish line. I didn’t call off the race, or change the rules. So, what did I tell them? 1. At Amy’s house, he set his winding watch. 2. The watchman was fired because he could only have had the dream while sleeping at work (night watch.) The question doesn’t ask how he knew the man knew the plane was going to crash. 3. He stayed inside the church. 4. He waited until nightfall, then exited through the first door. 5. They changed horses. ---
**Author:** ![jinty](https://avatars.discourse-cdn.com/v4/letter/j/dbc845/32.png) [@jinty](https://boards.straightdope.com/u/jinty)\ **Post date:** [July 27, 2010, 12:57pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/23 "2010-07-27T12:57:15Z")
1. Before he leaves his own house, he notes the time the clocks stopped at. When he gets to Amy’s house, the time difference between his stopped clocks and her her running clocks tells him how long it took him to walk from one house to the other. ---
**Author:** ![KennerTheGreat](https://avatars.discourse-cdn.com/v4/letter/k/a8b319/32.png) [@KennerTheGreat](https://boards.straightdope.com/u/KennerTheGreat)\ **Post date:** [July 27, 2010, 1:12pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/24 "2010-07-27T13:12:05Z")
I think all the correct answers are up already, but I’ll put the ones I was looking for. [spoiler]1. Today is December 1. Johnny’s birthday is on December 31. The day before yesterday he was 9, yesterday he turned 10, this year he’ll turn 11 and next year he’ll turn 12. 1. Amy gave Brian a watch. 2. By telling me about his dream, the watchman unwittingly admitted he’d been sleeping on the job. 3. The six men were pallbearers carrying a body in a coffin. 4. Tom waited until night, then left through the glass room. 5. They got up on each other’s horses.[/spoiler] ---
**Author:** ![notfrommensa](https://avatars.discourse-cdn.com/v4/letter/n/f14d63/32.png) [@notfrommensa](https://boards.straightdope.com/u/notfrommensa)\ **Post date:** [July 27, 2010, 2:25pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/25 "2010-07-27T14:25:00Z")
1. Is today December 1? or January 1? 2. If Amy gave Brian a watch, how come he didn’t know how long it had taken to get home? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 27, 2010, 4:40pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/26 "2010-07-27T16:40:55Z")
> [@](#): > > 1. If Amy gave Brian a watch, how come he didn’t know how long it had taken to get home? Because he didn’t look at it right exactly when he left Amy’s, or exactly when he got home. I mean, I always wear a watch, and I don’t know exactly how long it takes me to get to or from the office: I’ve never had reason to time it. And I’m not sure I like the pallbearer answer (although it obviously fits in with six wet men and them all leaving a church specifically). I’ve never heard of pallbearers running. If it starts raining, then you walk in the rain. ---
**Author:** ![BobLibDem](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/boblibdem/32/3149_2.png) [@BobLibDem](https://boards.straightdope.com/u/BobLibDem)\ **Post date:** [July 27, 2010, 4:46pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/27 "2010-07-27T16:46:01Z")
I maintain that number 2 is impossible. One cannot set a clock to the exact time. I can conceive of ways he could do it to within a minute more or less but to the millisecond, no. ---
**Author:** ![Delayed\_Reflex](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/delayed_reflex/32/3172_2.png) [@Delayed\_Reflex](https://boards.straightdope.com/u/Delayed_Reflex)\ **Post date:** [July 27, 2010, 4:53pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/28 "2010-07-27T16:53:47Z")
My first thought for #5: There was a 3rd door in the room that was safe to exit through. It was never specified that there were ONLY two doors 😉 The expected answer is definitely better though. ---
**Author:** ![Staver808](https://avatars.discourse-cdn.com/v4/letter/s/cc9497/32.png) [@Staver808](https://boards.straightdope.com/u/Staver808)\ **Post date:** [August 6, 2010, 12:53am UTC](https://boards.straightdope.com/t/brain-teasers/548065/29 "2010-08-06T00:53:59Z")
Well my answer for #2 was that he just took one of his clocks over to Amy’s and a bunch of extention cords. It seemed the obvious answer to me. ---
**Author:** ![Shagnasty](https://avatars.discourse-cdn.com/v4/letter/s/9dc877/32.png) [@Shagnasty](https://boards.straightdope.com/u/Shagnasty)\ **Post date:** [August 6, 2010, 1:44am UTC](https://boards.straightdope.com/t/brain-teasers/548065/30 "2010-08-06T01:44:17Z")
> [@BobLibDem](#): > > I maintain that number 2 is impossible. One cannot set a clock to the exact time. I can conceive of ways he could do it to within a minute more or less but to the millisecond, no. True. I think several of these have more than one correct answer like many questions of this type do. There is the ‘dumb’ answer that only someone with common sense could use to figure out the problem in the real world. There is the ‘smart’ answer that the question askers are looking for yet is often still technically wrong, dumb, or both and then there is the very deep answer that is for pot smoking majors or your average Doper in one of these threads. Manually setting an exact time on one clock versus another is an impossibility because of the theory of special relativity and the fact that time doesn’t exist by itself but only as a component of space-time. The question makes no sense at all. You can’t synchronize clocks exactly without taking relativity into account and we don’t know if Amy’s house is next door or 3.14159265 parsecs down the road. Whoever wrote that question should be sent back to their grad school for a refund. :snort: ---
**Author:** ![glowacks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/glowacks/32/5548_2.png) [@glowacks](https://boards.straightdope.com/u/glowacks)\ **Post date:** [August 8, 2010, 3:40am UTC](https://boards.straightdope.com/t/brain-teasers/548065/31 "2010-08-08T03:40:51Z")
For 2, I came up with the idea that Amy’s electronic devices were _also_ disrupted and restarted at the same time, and thus give the same time as the ones at his house. Amy has a watch and Brian doesn’t; all he needed to know was what the time difference between the disrupted clocks and the actual time was. Of course, this assumes that the time advances regularly after the power has been restored, which is not a great assumption. For 5, I don’t like the “wait for night” answer, because that assumes that Tom _can_ wait for night. Tom is already established as being in a fantasy world if there’s a dragon behind one door, so the sun might never set - suppose it’s on a planet with with rotation equal to revolution time. It’s never said that Tom knows what’s behind each door, or that he’s able to tell whether the sun is down. You need to make a number of assumptions that are not obvious in order for “wait for night” to make sense. 6 is misleading. One could easily say that part of “the rules” is that you ride your own horse, or that whichever horse you’re riding is “yours”, much like how the “owner” of a card in a collectible card game is generally defined as the player who started with it in their deck, not the actual legal owner of the card. Additionally, saying that they jumped up on the horses without mentioning they jumped on the opposite ones implicitly assumes that they jumped on their own. Very very very misleading, to the point where I intuitively knew the answer before I read the last line, then decided my answer didn’t work since it required “changing the rules”. ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [August 8, 2010, 6:06am UTC](https://boards.straightdope.com/t/brain-teasers/548065/32 "2010-08-08T06:06:09Z")
> [@MeanOldLady](#): > > I feel the same way, but everyone else spoilered theirs, and I didn’t want to come in a piss on everyone’s parade. Don’t worry, only the first six paraders will get wet. ---
**Author:** ![Chessic\_Sense](https://avatars.discourse-cdn.com/v4/letter/c/7c8e57/32.png) [@Chessic\_Sense](https://boards.straightdope.com/u/Chessic_Sense)\ **Post date:** [August 10, 2010, 3:34pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/33 "2010-08-10T15:34:11Z")
As a connoiseur of these, it’s been a long time since I’ve heard a lateral thinking puzzle that I’d never heard before. I’d appreciate it if people posted some more. Surely there’s a new one out there somewhere. ---
**Author:** ![Left\_Hand\_of\_Dorkness](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/left_hand_of_dorkness/32/7156_2.png) [@Left\_Hand\_of\_Dorkness](https://boards.straightdope.com/u/Left_Hand_of_Dorkness)\ **Post date:** [August 11, 2010, 1:39pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/34 "2010-08-11T13:39:40Z")
My favorite is something like this. I think I’ve posted it hereabouts before. Bob has a square pond, and he planted a tree at each corner. Now the trees are big and beautiful, and he really likes the trees. And he really likes the pond. He likes its square shape. But it’s not big enough for him. He wants to make it twice as big as it currently is (surface-area-wise). But he doesn’t want to cut down or even move the trees. And he definitely doesn’t want to change the shape of the pond: he loves the square pond. Can he do it? If so, how? ---
**Author:** ![Tom\_Scud](https://avatars.discourse-cdn.com/v4/letter/t/f08c70/32.png) [@Tom\_Scud](https://boards.straightdope.com/u/Tom_Scud)\ **Post date:** [August 11, 2010, 1:46pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/35 "2010-08-11T13:46:49Z")
> [@Left\_Hand\_of\_Dorkness](#): > > My favorite is something like this. I think I’ve posted it hereabouts before. > > Bob has a square pond, and he planted a tree at each corner. Now the trees are big and beautiful, and he really likes the trees. And he really likes the pond. He likes its square shape. > > But it’s not big enough for him. He wants to make it twice as big as it currently is (surface-area-wise). But he doesn’t want to cut down or even move the trees. And he definitely doesn’t want to change the shape of the pond: he loves the square pond. > > Can he do it? If so, how? In example-land, he can, by [spoiler]making it into a square pond with a tree at the center of each side. In non-example land, I can’t help thinking that would seriously mess with the trees’ root structure.[/spoiler] ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 11, 2010, 4:19pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/36 "2010-08-11T16:19:46Z")
Even if he doesn’t want to move the trees, there’s nothing that says he can’t move the pond. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [August 11, 2010, 5:25pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/37 "2010-08-11T17:25:58Z")
A man has four trees in his garden. It is exactly ten yards from \*any \* of the trees to _all three_ of the others. How is this possible? (Assume all the trees are mathematical points. 🙂 ) ---
**Author:** ![Drain\_Bead](https://avatars.discourse-cdn.com/v4/letter/d/e47774/32.png) [@Drain\_Bead](https://boards.straightdope.com/u/Drain_Bead)\ **Post date:** [August 11, 2010, 5:28pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/38 "2010-08-11T17:28:58Z")
My first thought for #2 was that Brian got home at high noon. ---
**Author:** ![Indistinguishable](https://avatars.discourse-cdn.com/v4/letter/i/90ced4/32.png) [@Indistinguishable](https://boards.straightdope.com/u/Indistinguishable)\ **Post date:** [August 11, 2010, 6:15pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/39 "2010-08-11T18:15:31Z")
> [@Malacandra](#): > > A man has four trees in his garden. It is exactly ten yards from \*any \* of the trees to _all three_ of the others. How is this possible? (Assume all the trees are mathematical points. 🙂 ) The man has a multistory garden, with the trees arranged tetrahedrally? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 11, 2010, 7:34pm UTC](https://boards.straightdope.com/t/brain-teasers/548065/40 "2010-08-11T19:34:12Z")
Or an implausibly steep hill or pit. [Previous page](https://boards.straightdope.com/t/brain-teasers/548065.md?page=1) [Next page](https://boards.straightdope.com/t/brain-teasers/548065.md?page=3)