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I believe that the author misremembers the common solution for the first question > 3 hens lay 3 eggs in 3 days. How many eggs do 12 hens give in 12 days? > [
by glofish 3y ago
I believe that the author misremembers the common solution for the first question
> 3 hens lay 3 eggs in 3 days. How many eggs do 12 hens give in 12 days?
> [...] When we got to it, everybody shouted "Three!"
I don't see why the "common" wrong answer would be 3. Why would anybody think that? The problem looks like this 3, 3 -> 3
When we see the 12 and 12 the intuitive, common, wrong answer should be 12 eggs.
That's what makes sense IMHO.
- menzoic 3y agothe article says everyone shouted 12 not Three
- forbiddenlake 3y agoIt said 3 originally. https://news.ycombinator.com/item?id=35688034 https://news.ycombinator.com/item?id=35688034
- mlajtos 3y agoOf course it was "Twelve!". Thank you for bringing this up. It is fixed now.
- moondrek 3y agoI read it as the students being familiar with a similar "trick" question and erroneously pattern matching on that. Another similar riddle goes like: "If it takes 5 machines 5 minutes to make 5 widgets, how long would it take 100 machines to make 100 widgets?" The correct answer there being "5 minutes", and the intuitive wrong answer being "100" as per your post. That would make sense as to why the teacher also expected "3", since they should be familiar with the existence of their non-intuitive questions, even if they misremember the specific non-intuition.
- Cthulhu_ 3y agoOr as to why adding more people to a late project makes it later: 1 woman takes 9 months to grow a baby, how long does it take 9 women to grow a baby?
- thechao 3y agoI took me surprisingly long to convince myself the author was correct: the answer is 48 because there's 4x as many hens and 4x as many days: 3 x 4 x 4 = 48. The "wrong" way to solve this problem is to compute hen-laying in terms of hen-egg-days, and then scaling.
- mlajtos 3y agoThere is a visual illustration in the article. I thought it might be useful for understating why it's 48.
- deleted 3y ago[deleted]
- hgsgm 3y agoThat's because it's output/input = eggs/(hen*day), not eggs/(hen/day), which is clear from meaning and logic if you aren't a GPT 2 LLM
- c22 3y agoI dunno, I immediately noted that 12 hens must lay 12 eggs in 3 days (it takes 3 days for a hen to lay an egg). Then I just asked myself how many 3-days are in 12-days--okay, 12 [eggs] * 4 [3-day egg periods] = 48... I didn't need to resort to pen and paper, but I'm also not in primary school.
- jimmaswell 3y agoI always skip straight to dimensional analysis for such a thing. 3 eggs / 3 chickens / 3 days * 12 chickens * 12 days cancels out to 48 eggs
- jkubicek 3y agoThere are a lot of right ways to solve this problem, but this is clearly the most fun way.
- 3y ago
- photochemsyn 3y agoHow to annoy the teacher: > "Ovulation (release of the yolk from the ovary) occurs every 24 – 26 hours regardless of fertilization (so a rooster is not needed). A hen ovulates a new yolk after the previous egg was laid. It takes 26 hours for an egg to fully form (white and shell added), so a hen will lay an egg later and later each day. Eventually the hen will lay too late in a day for ovulation to be signaled. She will then skip a day or more before laying another egg." (UWisconsin Livestock) So, the 3 hens must have been at the least productive point in their egg-laying cycle over the initial three-day time period... Now if we have the two-hour daily offset, over 12 days, ummm, maybe two or three days skipped per hen? So, ah, 108-120 eggs is what the farmer could expect from the 12 hens?
- ouid 3y agoHe misremebered the third task as well, since his solution to it, as stated, is wrong. If you aren't given that every card has a number on one side and a color on the other, then you need to check everything which does not satisfy the consequent.
- mlajtos 3y agoI added "We have cards with a number and color on each face." to the task statement. Hope this makes rules clearer as I could not phrase it better.
- ouid 3y agoThe rules were clear before, what has changed is that they are now different rules. You were just wrong before. You've still got a problem though, now when you ask the reader to verify the rule, you have to explicitly state that they're not trying to verify the first rule.
- mlajtos 3y agoOh shit, you are right. Added a completely explicit statement under the problem question. In both situations. Thank you for pointing this out.