# Help with a logic test **URL:** \ **Category:** Factual Questions\ **Created:** [August 18, 2010, 7:21pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657 "2010-08-18T19:21:38Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Nausicaa](https://avatars.discourse-cdn.com/v4/letter/n/7c8e57/32.png) [@Nausicaa](https://boards.straightdope.com/u/Nausicaa)\ **Post date:** [August 18, 2010, 7:21pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/1 "2010-08-18T19:21:38Z")
I was on a job interview and I was required a couple of tests - some of it was general information, some math and some logic. I did OK except for this one - I spent about 20 minutes on it before I gave up and wrote down a guess. Can anyone give me a hand on this? A fish’s head is 9" long. The tail is the length of the head plus 1/2 the body. The body is the length of the head and the tail. What is the total length of the fish? Nausicaa ---
**Author:** ![Trepa\_Mayfield](https://avatars.discourse-cdn.com/v4/letter/t/edb3f5/32.png) [@Trepa\_Mayfield](https://boards.straightdope.com/u/Trepa_Mayfield)\ **Post date:** [August 18, 2010, 7:25pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/2 "2010-08-18T19:25:06Z")
Is the length of the body the length of the fish, or is the fish head + body + tail? [spoiler] head is 9 inches body is 36 inches tail is 27 inches therefore, either the fish is 36 inches, or it is 9 + 36 + 27 = 72 inches[/spoiler] ---
**Author:** ![Mosier](https://avatars.discourse-cdn.com/v4/letter/m/7ea924/32.png) [@Mosier](https://boards.straightdope.com/u/Mosier)\ **Post date:** [August 18, 2010, 7:32pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/3 "2010-08-18T19:32:42Z")
Algebra would look like this. T = tail, B = body. 9 + 1/2B = T 9 + T = B Then you can just solve for 2 variables. ---
**Author:** ![godix](https://avatars.discourse-cdn.com/v4/letter/g/278dde/32.png) [@godix](https://boards.straightdope.com/u/godix)\ **Post date:** [August 18, 2010, 7:40pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/4 "2010-08-18T19:40:24Z")
Turn it into a math problem Total length of fish = H + T + B H for head 9 T for tail length 9 + 1/2B B for body length 9 + T Solve for Body length, first substitute in the equation for tail then just do the algebra B = 9 + T B = 9 + (9 + 1/2B) B = 18 + 1/2B 1/2b = 18 B = 36 Now that you have B, plug it into the equation for T T = 9 + 1/2B T = 9 + 1/2(36) T = 9 + 18 T = 27 So know we know all 3 variables, substitute into H + B + T 9 + 36 + 27 The fish is 72 inches long ---
**Author:** ![Thudlow\_Boink](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/thudlow_boink/32/320_2.png) [@Thudlow\_Boink](https://boards.straightdope.com/u/Thudlow_Boink)\ **Post date:** [August 18, 2010, 7:40pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/5 "2010-08-18T19:40:46Z")
ETA: The above answers were posted while I was typing mine, which essentially just repeats what they say. > [@Nausicaa](#): > > The tail is the length of the head plus 1/2 the body. t = 9 + (1/2)b > [@](#): > > The body is the length of the head and the tail. b = 9 + t Substituting 9 + (1/2)b for t in the second equation yields b = 9 + 9 + (1/2)b Solving for b gives b = 36. Then t = 27 Total = 9 + 36 + 27 ---
**Author:** ![Nausicaa](https://avatars.discourse-cdn.com/v4/letter/n/7c8e57/32.png) [@Nausicaa](https://boards.straightdope.com/u/Nausicaa)\ **Post date:** [August 18, 2010, 7:47pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/6 "2010-08-18T19:47:02Z")
Thanks! I was close but I just couldn’t quite get it. ---
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [August 18, 2010, 8:28pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/7 "2010-08-18T20:28:19Z")
The implication is that body does not include head nor tail, the way I read it? Very badly worded. One would assume a fish body includes the head. The whole is stupid because how do you tell where a fish head ends? (End of the gils?) How many fish other than maybe a Manta have a tail over half the length of the body? (For a Manta, I’d call it the stinger maybe, not a tail?) “Fred’s feet are the length of his head plus half the length of his body…” ---
**Author:** ![running\_coach](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/running_coach/32/15836_2.png) [@running\_coach](https://boards.straightdope.com/u/running_coach)\ **Post date:** [August 18, 2010, 8:34pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/8 "2010-08-18T20:34:00Z")
325F for 20 min, season with a little lemon juice and dill. Eat the fish. Problem solved. 😃 ---
**Author:** ![Omar\_Little](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/omar_little/32/269_2.png) [@Omar\_Little](https://boards.straightdope.com/u/Omar_Little)\ **Post date:** [August 18, 2010, 8:55pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/9 "2010-08-18T20:55:50Z")
72" ---
**Author:** ![Cheshire\_Human](https://avatars.discourse-cdn.com/v4/letter/c/5f8ce5/32.png) [@Cheshire\_Human](https://boards.straightdope.com/u/Cheshire_Human)\ **Post date:** [August 18, 2010, 9:11pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/10 "2010-08-18T21:11:33Z")
I got the same as everyone else, 72. That said, I think this: > [@runner pat](#): > > 325F for 20 min, season with a little lemon juice and dill. Eat the fish. > > Problem solved. 😃 Should also have concluded “That’s one hell of a big fish… Recipe feeds 24, use a bigger oven.” 😃 ---
**Author:** ![Indian](https://avatars.discourse-cdn.com/v4/letter/i/c0e974/32.png) [@Indian](https://boards.straightdope.com/u/Indian)\ **Post date:** [August 19, 2010, 6:32am UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/11 "2010-08-19T06:32:33Z")
[quote=“md2000, post:7, topic:550657”] The implication is that body does not include head nor tail, the way I read it? Very badly worded. One would assume a fish body includes the head. The whole is stupid because how do you tell where a fish head ends? (End of the gils?) How many fish other than maybe a Manta have a tail over half the length of the body? (For a Manta, I’d call it the stinger maybe, not a tail?) QUOTE] Seconded . Very badly worded problem . Body does not include head & tail ? :eek: ---
**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:** [August 19, 2010, 6:40am UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/12 "2010-08-19T06:40:17Z")
> [@Nausicaa](#): > > I was on a job interview and I was required a couple of tests - some of it was general information, some math and some logic. I did OK except for this one - I spent about 20 minutes on it before I gave up and wrote down a guess. Can anyone give me a hand on this? I got the same answer as everyone else. I want to know where you went that gave you this question, 'cause I would so kick ass at that interview. ---
**Author:** ![penultima\_thule](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/penultima_thule/32/3833_2.png) [@penultima\_thule](https://boards.straightdope.com/u/penultima_thule)\ **Post date:** [August 19, 2010, 10:15am UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/13 "2010-08-19T10:15:38Z")
> [@runner pat](#): > > 325F for 20 min, season with a little lemon juice and dill. Eat the fish. > > Problem solved. 😃 No, that’s simply wrong. It will take much more than 20 minutes. 😉 Apparently the all-tackle angling record Striped bass, taken in New Jersey in 1972, weighed 78 ½ pounds and measured 72 inches long [http://www.philthylou.com/About%20the%20fish.htm](http://www.philthylou.com/About%20the%20fish.htm) ---
**Author:** ![CurtC](https://avatars.discourse-cdn.com/v4/letter/c/ce73a5/32.png) [@CurtC](https://boards.straightdope.com/u/CurtC)\ **Post date:** [August 19, 2010, 2:22pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/14 "2010-08-19T14:22:04Z")
I interpreted “The body is the length of the head and the tail” to mean that the entire fish is the head plus the tail; IOW the fish’s body is divided up into the head and the tail. Then I got 36" as the answer. ---
**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:** [August 19, 2010, 2:38pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/15 "2010-08-19T14:38:22Z")
This is one of those lateral thinking puzzles. The correct answer is, “Give a man a fish and you feed him for a day; teach a man to fish and you feed him for a lifetime.” ---
**Author:** ![mozchron](https://avatars.discourse-cdn.com/v4/letter/m/c2a13f/32.png) [@mozchron](https://boards.straightdope.com/u/mozchron)\ **Post date:** [August 19, 2010, 2:49pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/16 "2010-08-19T14:49:26Z")
The fish is 72 inches long. 3 parts to the fish: the Head (H), the Body (B) and the tail (T). I set B = X, there are other ways to do it as well but this works fine. This information was given in the problem: H = 9" B = H+T = X T = H+0.5B = 9+0.5X Now solve for B (i.e., solve for X) X = H+T X = 9+9+0.5X X = 18+0.5X X - 0.5X = 18 X = (18/0.5) X = 36 = B So… H = 9 B = 36 T = H+0.5B = 9+(0.5\*36) = 27 9+36+27 = 72 inches. ---
**Author:** ![mozchron](https://avatars.discourse-cdn.com/v4/letter/m/c2a13f/32.png) [@mozchron](https://boards.straightdope.com/u/mozchron)\ **Post date:** [August 19, 2010, 3:05pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/17 "2010-08-19T15:05:29Z")
doh! didn’t see godix’s excellent post above. ---
**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 19, 2010, 3:23pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/18 "2010-08-19T15:23:30Z")
People, people, please. The question says “The body IS the length of the head and the tail.” It doesn’t say “The body is equal to…” The fish has a body. Some of it is head, some of it is tail, but everything is either one or the other. H = 9 T = 9 + (H +T)/2 2(T-9)= H + T T = H + 18 T = 27 H = 9 So B = 36", not 72", because fish=body. Fish != head+body+tail. ---
**Author:** ![mozchron](https://avatars.discourse-cdn.com/v4/letter/m/c2a13f/32.png) [@mozchron](https://boards.straightdope.com/u/mozchron)\ **Post date:** [August 19, 2010, 3:35pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/19 "2010-08-19T15:35:05Z")
> [@Chessic\_Sense](#): > > People, people, please. The question says “The body IS the length of the head and the tail.” It doesn’t say “The body is equal to…” > > The fish has a body. Some of it is head, some of it is tail, but everything is either one or the other. > > H = 9 > T = 9 + (H +T)/2 > 2(T-9)= H + T > T = H + 18 > > T = 27 > H = 9 > So B = 36", not 72", because fish=body. Fish != head+body+tail. Hm… that is an interesting interpretation of the question that I hadn’t considered. Very poorly worded in my opinion. ---
**Author:** ![CookingWithGas](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cookingwithgas/32/485_2.png) [@CookingWithGas](https://boards.straightdope.com/u/CookingWithGas)\ **Post date:** [August 19, 2010, 3:43pm UTC](https://boards.straightdope.com/t/help-with-a-logic-test/550657/20 "2010-08-19T15:43:08Z")
> [@Chessic\_Sense](#): > > The fish has a body. Some of it is head, some of it is tail, but everything is either one or the other. Have you ever eaten a fish? :dubious: BTW we don’t know if the language given by the OP is exactly the wording on the test. [Next page](https://boards.straightdope.com/t/help-with-a-logic-test/550657.md?page=2)