# Lateral thinking puzzles **URL:** \ **Category:** The Game Room\ **Created:** [October 8, 2009, 2:03am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008 "2009-10-08T02:03:18Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Malleus\_Incus\_Stapes](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/malleus_incus_stapes/32/3293_2.png) [@Malleus\_Incus\_Stapes](https://boards.straightdope.com/u/Malleus_Incus_Stapes)\ **Post date:** [October 8, 2009, 2:03am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/1 "2009-10-08T02:03:18Z")
I need some good lateral thinking puzzles- not situational riddles like “A man is found dead in a puddle of water; what happened?”, but something like the [think outside the box](http://en.wikipedia.org/wiki/Thinking_outside_the_box) puzzle. The stuff they use in psychological tests to see how flexible you are. ---
**Author:** ![Zsofia](https://avatars.discourse-cdn.com/v4/letter/z/7bcc69/32.png) [@Zsofia](https://boards.straightdope.com/u/Zsofia)\ **Post date:** [October 8, 2009, 3:49am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/2 "2009-10-08T03:49:28Z")
Damn, I was hoping it was going to be the “a man is found dead in the middle of a field with an unopened package. How did he die?” kind. I love those, even though they never play fair. ---
**Author:** ![Isamu](https://avatars.discourse-cdn.com/v4/letter/i/7c8e57/32.png) [@Isamu](https://boards.straightdope.com/u/Isamu)\ **Post date:** [October 8, 2009, 4:22am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/3 "2009-10-08T04:22:00Z")
Google “microsoft interview questions” for a whole host of questions that require a lot of thinking outside the box. For example, why is a manhole cover round? One question I like to ponder is “What is the best way to move Mt Fuji from its present location to the US?” ---
**Author:** ![bouv](https://avatars.discourse-cdn.com/v4/letter/b/bc8723/32.png) [@bouv](https://boards.straightdope.com/u/bouv)\ **Post date:** [October 8, 2009, 4:36am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/4 "2009-10-08T04:36:45Z")
> [@Isamu](#): > > For example, why is a manhole cover round? [spoiler]A few reasons. 1. The main reason I’ve heard is that a square cover can fall through the hole, since the diagonal is longer than the edge. A round cover can’t do this. 2. A round cover can easily be rolled around. 3. Round things are easier to manufacture [/spoiler] > [@Isamu](#): > > One question I like to ponder is “What is the best way to move Mt Fuji from its present location to the US?” Not a fucking clue. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [October 8, 2009, 4:37am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/5 "2009-10-08T04:37:40Z")
I heard one that had a good answer, and then later I found a flaw with the answer. You have a rectangular sheet cake. A piece has been cut out of the cake somewhere, and removed. How do you divide the remaining cake into two equal pieces with one, straight cut? (The answer is not to remove it from the pan and cut horizontally.) ---
**Author:** ![cormac262](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@cormac262](https://boards.straightdope.com/u/cormac262)\ **Post date:** [October 8, 2009, 4:48am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/6 "2009-10-08T04:48:11Z")
Do you mean this kind of puzzle ?: Being chased through the jungle at night by man-eating savages, your party of 4 come to a broken down bridge spanning a river gorge. Each of your party can cross the bridge at a different rate: - person A can cross in 1 minute - person B requires 2 minutes - person C requires 5 minutes - person D requires 10 minutes You only have 1 flashlight. And due to missing planks, the flashlight must be used on every crossing of the bridge. The bridge can only support 2 people maximum on each crossing. (Since you only have 1 flashlight, the time required for each crossing is determined by the slower of the two people). The river gorge is too wide to throw the flashlight across. Based on careful computation of the rate the savages are gaining on you, you only have 17 minutes to get all of your party across the bridge. Once you all get across, you can cut the bridge and you’re safe (the gorge is also too wide for them to throw their spears across 😉 How do you get all 4 of your party across in 17 minutes ? (Note: there is no “trick” answer - no juggling one of your group so only “2” are “on” the bridge at any given time, no making a torch so that the flashlight doesn’t have to come back, no memorizing the location of the holes in the bridge, etc.) ---
**Author:** ![Bosstone](https://avatars.discourse-cdn.com/v4/letter/b/22d042/32.png) [@Bosstone](https://boards.straightdope.com/u/Bosstone)\ **Post date:** [October 8, 2009, 4:53am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/7 "2009-10-08T04:53:38Z")
> [@Robot\_Arm](#): > > (The answer is not to remove it from the pan and cut horizontally.) Why not? That seems like a perfectly good outside-the-box question. ---
**Author:** ![Justin\_Credible](https://avatars.discourse-cdn.com/v4/letter/j/a8b319/32.png) [@Justin\_Credible](https://boards.straightdope.com/u/Justin_Credible)\ **Post date:** [October 8, 2009, 4:57am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/8 "2009-10-08T04:57:10Z")
> [@Isamu](#): > > Google “microsoft interview questions” for a whole host of questions that require a lot of thinking outside the box. > > For example, why is a manhole cover round? > > One question I like to ponder is “What is the best way to move Mt Fuji from its present location to the US?” Conquer Japan? Or just name something in the US “Mt Fuji” and change the name of the current one. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [October 8, 2009, 4:59am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/9 "2009-10-08T04:59:17Z")
> [@Bosstone](#): > > Why not? That seems like a perfectly good outside-the-box question. Because that’s the way it was told to me. Also, some of these puzzles have been around for a while. I’ve heard the “cut it horizontally” answer before. The point is to think, not just to remember. ---
**Author:** ![Argent\_Towers](https://avatars.discourse-cdn.com/v4/letter/a/e8c25b/32.png) [@Argent\_Towers](https://boards.straightdope.com/u/Argent_Towers)\ **Post date:** [October 8, 2009, 5:01am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/10 "2009-10-08T05:01:40Z")
A farmer has a fox, a chicken, and a bag of grain. He has to get them from one side of a river to the other, in a rowboat which can only transport one of them at a time. What is the best way to do this? The correct answer is: Why the fuck does the farmer have a fox? ---
**Author:** ![G.Pie](https://avatars.discourse-cdn.com/v4/letter/g/bb73d2/32.png) [@G.Pie](https://boards.straightdope.com/u/G.Pie)\ **Post date:** [October 8, 2009, 6:18am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/11 "2009-10-08T06:18:39Z")
[deleted, can’t make the diagram show correctly] ---
**Author:** ![jjimm](https://avatars.discourse-cdn.com/v4/letter/j/ba8739/32.png) [@jjimm](https://boards.straightdope.com/u/jjimm)\ **Post date:** [October 8, 2009, 6:56am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/12 "2009-10-08T06:56:37Z")
> [@cormac262](#): > > How do you get all 4 of your party across in 17 minutes ? Got it! [spoiler]1 and 2 go across, 1 comes back with the flashlight. Elapsed time: 3 mins. 5 and 10 now cross. Elapsed time: 13 mins. 2 returns to 1 with the flashlight. Elapsed time: 15 mins. 1 and 2 cross to the other side. Elapsed time: 17 mins. It’s the masking of the second-longest crossing time by the longest that is the counterintuitive thing.[/spoiler] My brain hurt working that out. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [October 8, 2009, 7:17am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/13 "2009-10-08T07:17:35Z")
I had a book once with four or five alternate answers to the nine-dots problem. > [@cormac262](#): > > Based on careful computation of the rate the savages are gaining on you, you only have 17 minutes to get all of your party across the bridge. Once you all get across, you can cut the bridge and you’re safe (the gorge is also too wide for them to throw their spears across 😉 Why cut the bridge? The savages won’t be able to cross it to follow you. You ever see a savage with a flashlight? For that matter, do you have to be all the way across within 17 minutes; what if you’re halfway across when the savages get to the bridge? They can’t follow you, because that’ll overload the bridge and they’ll die. Can they throw a spear halfway? In that case, leave one of your party at the midpoint and pass the flashlight back across the chasm in two throws (an admittedly risky strategy). Is that lateral enough for you. ---
**Author:** ![Noone\_Special](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/noone_special/32/2863_2.png) [@Noone\_Special](https://boards.straightdope.com/u/Noone_Special)\ **Post date:** [October 8, 2009, 7:17am UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/14 "2009-10-08T07:17:42Z")
> [@cormac262](#): > > Do you mean this kind of puzzle ?: > > Being chased through the jungle at night by man-eating savages, your party of 4 come to a broken down bridge spanning a river gorge. > > Each of your party can cross the bridge at a different rate: > > - person A can cross in 1 minute > - person B requires 2 minutes > - person C requires 5 minutes > - person D requires 10 minutes > > You only have 1 flashlight. And due to missing planks, the flashlight must be used on every crossing of the bridge. > > The bridge can only support 2 people maximum on each crossing. (Since you only have 1 flashlight, the time required for each crossing is determined by the slower of the two people). > > The river gorge is too wide to throw the flashlight across. > > Based on careful computation of the rate the savages are gaining on you, you only have 17 minutes to get all of your party across the bridge. Once you all get across, you can cut the bridge and you’re safe (the gorge is also too wide for them to throw their spears across 😉 > > How do you get all 4 of your party across in 17 minutes ? > > (Note: there is no “trick” answer - no juggling one of your group so only “2” are “on” the bridge at any given time, no making a torch so that the flashlight doesn’t have to come back, no memorizing the location of the holes in the bridge, etc.) A & B cross – 2 minutes. A returns – 3 minutes C & D cross – 13 minutes. B, who was left at the other end, returns with the flashlight – 15 minutes A & B cross – 17 minutes. (alternatively, B returns after the first crossing, and A returns after the second – it doesn’t matter) The secret is \*\*not \*\*to try and minimize the return time by sending A sequentially with each of the others. ---
**Author:** ![Shodan](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shodan](https://boards.straightdope.com/u/Shodan)\ **Post date:** [October 8, 2009, 12:18pm UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/15 "2009-10-08T12:18:19Z")
> [@Justin\_Credible](#): > > > [@Isamu](#): > > > > One question I like to ponder is “What is the best way to move Mt Fuji from its present location to the US?” > > Conquer Japan? Or just name something in the US “Mt Fuji” and change the name of the current one. I was going to say “sell Mt. Fuji to the US and declare it a US national park”. These usually break down in quibbles over the definition of “easiest”. How the heck does one persuade the Japanese to sell or rename one of their most famous landmarks? Might be easier to conquer them. Regards, Shodan ---
**Author:** ![Half\_Man\_Half\_Wit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/half_man_half_wit/32/21766_2.png) [@Half\_Man\_Half\_Wit](https://boards.straightdope.com/u/Half_Man_Half_Wit)\ **Post date:** [October 8, 2009, 12:36pm UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/16 "2009-10-08T12:36:03Z")
This is somewhat well known, but I always liked ‘[petals around the rose](http://weavervsworld.com/docs/think/rose/)’. Took me forever to figure it out. ---
**Author:** ![otorophile](https://avatars.discourse-cdn.com/v4/letter/o/3ab097/32.png) [@otorophile](https://boards.straightdope.com/u/otorophile)\ **Post date:** [October 8, 2009, 1:08pm UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/17 "2009-10-08T13:08:27Z")
> [@Robot\_Arm](#): > > I had a book once with four or five alternate answers to the nine-dots problem. Well, what are they? > [@Half\_Man\_Half\_Wit](#): > > This is somewhat well known, but I always liked ‘[petals around the rose](http://weavervsworld.com/docs/think/rose/)’. Took me forever to figure it out. Usually I’m pretty slow with these things, but I got that instantly. ---
**Author:** ![cormac262](https://avatars.discourse-cdn.com/v4/letter/c/f14d63/32.png) [@cormac262](https://boards.straightdope.com/u/cormac262)\ **Post date:** [October 8, 2009, 2:59pm UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/18 "2009-10-08T14:59:42Z")
> [@Noone\_Special](#): > > A & B cross – 2 minutes. > A returns – 3 minutes > C & D cross – 13 minutes. > B, who was left at the other end, returns with the flashlight – 15 minutes > A & B cross – 17 minutes. > > (alternatively, B returns after the first crossing, and A returns after the second – it doesn’t matter) > > The secret is \*\*not \*\*to try and minimize the return time by sending A sequentially with each of the others. Ahem…the OP was requesting “puzzles” and not necessarily “answers” (should have used a spoiler box like jjimm) ---
**Author:** ![Indian](https://avatars.discourse-cdn.com/v4/letter/i/c0e974/32.png) [@Indian](https://boards.straightdope.com/u/Indian)\ **Post date:** [October 8, 2009, 3:09pm UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/19 "2009-10-08T15:09:45Z")
I didn’t see any rose or petals in that page ! ---
**Author:** ![Hampshire](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hampshire/32/4887_2.png) [@Hampshire](https://boards.straightdope.com/u/Hampshire)\ **Post date:** [October 8, 2009, 3:17pm UTC](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008/20 "2009-10-08T15:17:35Z")
This one was in the latest Professor Layton game. I got it fairly quick but still thought it was clever: A teacher has 10 students. She randomly places a red or blue hat on each student (they can not see their own hat). She then tells each student that if they can see 5 red hats or more they can have a red balloon. If they can not they get a blue balloon. In the end she handed out some red balloons and some blue balloons. How many students had blue hats on? [Next page](https://boards.straightdope.com/t/lateral-thinking-puzzles/513008.md?page=2)