# Advanced Man Mathematics **URL:** \ **Category:** In My Humble Opinion\ **Created:** [January 31, 2013, 10:48pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967 "2013-01-31T22:48:31Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Punoqllads](https://avatars.discourse-cdn.com/v4/letter/p/d2c977/32.png) [@Punoqllads](https://boards.straightdope.com/u/Punoqllads)\ **Post date:** [January 31, 2013, 10:48pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/1 "2013-01-31T22:48:31Z")
Three men enter a bathroom with 7 urinals. Assuming none of the men enter a stall, which urinal does the third man use? ---
**Author:** ![Ace309](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ace309/32/1050_2.png) [@Ace309](https://boards.straightdope.com/u/Ace309)\ **Post date:** [January 31, 2013, 11:10pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/2 "2013-01-31T23:10:14Z")
Can we all at least agree that the third urinal will never be #1 or #7, which should always be the first two filled? ---
**Author:** ![Dervorin](https://avatars.discourse-cdn.com/v4/letter/d/eb8c5e/32.png) [@Dervorin](https://boards.straightdope.com/u/Dervorin)\ **Post date:** [January 31, 2013, 11:21pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/3 "2013-01-31T23:21:17Z")
#4 is obviously the right answer, but #3 or #5 would also be acceptable. ---
**Author:** ![Antinor01](https://avatars.discourse-cdn.com/v4/letter/a/ecae2f/32.png) [@Antinor01](https://boards.straightdope.com/u/Antinor01)\ **Post date:** [January 31, 2013, 11:21pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/4 "2013-01-31T23:21:19Z")
3 or 5. This leaves the other of those two open in case a 4th enters, while maintaining a buffer between each. ---
**Author:** ![Lord\_Mondegreen](https://avatars.discourse-cdn.com/v4/letter/l/91b2a8/32.png) [@Lord\_Mondegreen](https://boards.straightdope.com/u/Lord_Mondegreen)\ **Post date:** [January 31, 2013, 11:37pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/5 "2013-01-31T23:37:10Z")
> [@Antinor01](#): > > 3 or 5. This leaves the other of those two open in case a 4th enters, while maintaining a buffer between each. Agreed. If you take 3 or 5 then there should be a 100% chance that the next person to come in will not stand beside you. If you take 4, then the next person in will have to stand next to exactly one person, so if he makes a random choice there is a 50% chance it will be you. ---
**Author:** ![crucible](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@crucible](https://boards.straightdope.com/u/crucible)\ **Post date:** [January 31, 2013, 11:40pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/6 "2013-01-31T23:40:57Z")
Two gentlemen of color standing side by each at urinals…“Man, the water in this bathroom is cold!”, “Deep, too”, says the other. ---
**Author:** ![crucible](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@crucible](https://boards.straightdope.com/u/crucible)\ **Post date:** [January 31, 2013, 11:43pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/7 "2013-01-31T23:43:38Z")
Many years ago, my fiance’ and I and her friend went to a state park for a picnic. While there, the ladies needed to use the ‘outhouse’, a large building with three doors. As soon as they entered, one on each end, I heard peals of laughter. When they came out I learned…three doors, 3 holes, no partitions. ---
**Author:** ![Max\_the\_Immortal](https://avatars.discourse-cdn.com/v4/letter/m/6de8d8/32.png) [@Max\_the\_Immortal](https://boards.straightdope.com/u/Max_the_Immortal)\ **Post date:** [February 1, 2013, 1:18am UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/8 "2013-02-01T01:18:28Z")
#3 or #5, because either has the potential to be slightly funny. ---
**Author:** ![Antinor01](https://avatars.discourse-cdn.com/v4/letter/a/ecae2f/32.png) [@Antinor01](https://boards.straightdope.com/u/Antinor01)\ **Post date:** [February 1, 2013, 3:00am UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/9 "2013-02-01T03:00:32Z")
> [@Lord\_Mondegreen](#): > > Agreed. If you take 3 or 5 then there should be a 100% chance that the next person to come in will not stand beside you. > > If you take 4, then the next person in will have to stand next to exactly one person, so if he makes a random choice there is a 50% chance it will be you. Agreed. Option 4 isn’t the advanced choice. ---
**Author:** ![snowthx](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowthx/32/10660_2.png) [@snowthx](https://boards.straightdope.com/u/snowthx)\ **Post date:** [February 1, 2013, 3:55am UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/10 "2013-02-01T03:55:15Z")
I would have answered #5, #6 or #7, because I assumed the first man went to urinal #1, second man would go to urinal #3, and the third man would have avoided #2 and #4 (space issue). ---
**Author:** ![Helena330](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/helena330/32/531_2.png) [@Helena330](https://boards.straightdope.com/u/Helena330)\ **Post date:** [February 1, 2013, 3:59am UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/11 "2013-02-01T03:59:28Z")
I learn something new every day. ---
**Author:** ![Speak\_to\_me\_Maddie](https://avatars.discourse-cdn.com/v4/letter/s/58956e/32.png) [@Speak\_to\_me\_Maddie](https://boards.straightdope.com/u/Speak_to_me_Maddie)\ **Post date:** [February 1, 2013, 4:01am UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/12 "2013-02-01T04:01:00Z")
The 1st man up would never use 1 or 7, he’d use 3,4, or 5. This leaves the next man to choose one or two beyond the buffer on either side, then the third man would take the other side of man 1 also with a buffer. 4 is the least likely to be used by the third man. ---
**Author:** ![Snowboarder\_Bo](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/snowboarder_bo/32/229_2.png) [@Snowboarder\_Bo](https://boards.straightdope.com/u/Snowboarder_Bo)\ **Post date:** [February 1, 2013, 5:23am UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/13 "2013-02-01T05:23:09Z")
[Male Restroom Etiquette](http://www.youtube.com/watch?v=IzO1mCAVyMw). Srsly, everything you need to know is in this video. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [February 1, 2013, 1:05pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/14 "2013-02-01T13:05:33Z")
I got the “winning answer,” but apparently via wrong reasoning. Was I the only one to assume first two men would go to #2 and #6 ? ---
**Author:** ![kayaker](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kayaker/32/441_2.png) [@kayaker](https://boards.straightdope.com/u/kayaker)\ **Post date:** [February 1, 2013, 1:18pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/15 "2013-02-01T13:18:50Z")
Sink. ---
**Author:** ![Leaffan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leaffan/32/299_2.png) [@Leaffan](https://boards.straightdope.com/u/Leaffan)\ **Post date:** [February 1, 2013, 1:22pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/16 "2013-02-01T13:22:17Z")
If I was the first man in I would go to number 1. If I was the second man in I would go to number 3 or 4. If I was the third man in I would go to number 7. ---
**Author:** ![Czarcasm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/czarcasm/32/4050_2.png) [@Czarcasm](https://boards.straightdope.com/u/Czarcasm)\ **Post date:** [February 1, 2013, 1:44pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/17 "2013-02-01T13:44:54Z")
The first man goes for the farthest one, #7. The second man will go for either #5 or #4, depending on how bathroom shy he is. The third man will will go for #2 every time because while he would like to leave a 2-urinal gap between him and the second man, he won’t pick the first urinal because it’s too close to the door. Studies have shown the urinal #1 is always the cleanest and least used urinal for that very reason. ---
**Author:** ![MrDibble](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mrdibble/32/114_2.png) [@MrDibble](https://boards.straightdope.com/u/MrDibble)\ **Post date:** [February 1, 2013, 1:58pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/18 "2013-02-01T13:58:48Z")
I assumed from the way the OP was phrased that the 3 men entered at the same time, the guy in the lead would take #1 (being lazy), man2 would go to #7 to maximise distance and man3 would split the difference and go to #4. The thought of what if another person entered after them didn’t occur to me (and wouldn’t, if I was man3) ---
**Author:** ![BigT](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bigt/32/12044_2.png) [@BigT](https://boards.straightdope.com/u/BigT)\ **Post date:** [February 1, 2013, 3:54pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/19 "2013-02-01T15:54:40Z")
Yeah, it does change on whether they enter at the same time or separately. Separately, it’ll be 7, then either 2 or 3 (as no one uses 1 if their are other choices), leaving the third man with 5. Together, it would be 7-5-3. Together, they all to to the end. Separately, the “furthest away” rule becomes an issue. And, yes, if they come in 2+1, it’s still properly 7-5-3, while 1+2 it’s 7-2-4/5, as the guy on 7 will be done soon enough so that everyone can still avoid 1. It’s not like peeing takes a lot of time or anything. ---
**Author:** ![MegaBee](https://avatars.discourse-cdn.com/v4/letter/m/f0a364/32.png) [@MegaBee](https://boards.straightdope.com/u/MegaBee)\ **Post date:** [February 1, 2013, 4:37pm UTC](https://boards.straightdope.com/t/advanced-man-mathematics/648967/20 "2013-02-01T16:37:41Z")
Is the seventh urinal one of those half-height ones? [Next page](https://boards.straightdope.com/t/advanced-man-mathematics/648967.md?page=2)