How is it wrong? My grandparents had hens and they got about one egg per day from each of them.
I have not kept accurate records but I estimate less than 1 in 40 gets it right. I have asked a lot of people. Many of them supposedly “highly educated.”
Also, I did say almost everyone.
Because according to the setup it takes a day and a half for a single chicken to lay an egg. Therefore any individual chicken will lay 4 eggs in 6 days; meaning you get 16 eggs in total over a span of 6 days.
The misdirection in the setup makes you think that a single chicken lays an egg per day, but that’s not what it says.
Right. It’s a failure to check one’s results. But if an answer comes to mind easily, people tend not to check their results, but rather just go with the immediate answer.
I have not kept accurate records but I estimate less than 1 in 40 gets it right. I have asked a lot of people. Many of them supposedly “highly educated.”
Also, I did say almost everyone.
Your grandparents got one egg per day from their chickens, but penultima thule gets one egg per day and a half from his chickens.
Back on topic, while the off-the-cuff pattern-recognition method is quicker (but sometimes wrong), and the analytic, algebraic method is usually right (but usually slower), those aren’t the only options. You can also start with the off-the-cuff method, and then check your answer. This lets you start acting on the quick answer before you’ve verified it (thus mitigating the increased time cost), but still gives you a chance to fix it if the check doesn’t work out, only spending the time on the full algebraic method when needed.
And in fact, for many more complicated algebra problems, this is how the algebraic solution works. You make an approximation, and then check to see if your approximation is good enough (and if it isn’t, then use your preliminary result to get a better approximation, until it is good enough, which usually only takes a small number of iterations).
It says a hen and a half, but that’s not uncommon when talking about statistics. Obviously heart disease can’t literally kill 198.8 people out of 100,000, but that’s the commonly quoted number.
I’m not sure how that relates to the portion of my post that you quoted. The problem as stated is mathematically correct, if misleading to the casual observer. When you say “a hen and a half lays an egg and a half in a day and a half” a casually observer is going to cancel out all the "a half"s and reduce the statement to “a hen lays an egg in a day”. But the whole point of the riddle’s misdirection is that you can’t reduce like that. You can only remove the first two, leaving “a hen lays an egg in a day and a half”, the time period doesn’t change. Most folks miss that and therein lies the magic of the riddle.
It’s the same type of misdirection in the OP’s riddle.
Your grandparents had Golden Comets, while penultima thule has Rhode Island Reds.
This reminds me of when my great-uncle visited and he told me the old puzzle about the three guys overpaying $30 for a $25 hotel room and the bellhop keeping $2 of the change – three people paid $9 = $27 and the bellhop kept $2 so WHERE’S THE MISSING DOLLAR??
I explained that it should be $27 - $2 = $25, not $27 + $2 = $30. My great-uncle paused and then said BUT WHERE’S THE MISSING DOLLAR??
I bet he went back to England and told people “I talked to a mathematician and even he couldn’t figure out where the MISSING DOLLAR is!!”
It is part of the joke to keep asking where the missing dollar is. Not everybody is asking that as part of the joke though.
At least bellhop problem is something people get a little interested in since it doesn’t sound like a question on a middle school math test that shuts off their mind immediately.
Sometimes it’s just as difficult to explain to a math-head why people get this wrong. They just keep saying, “Yeah, but it’s simple algebra, see let X be the price of one pencil…”, yet these highly educated people can’t grasp that most people don’t think that way.
When I read the OP, that’s how I did it. I started with the intuitive “oh, the expensive one is $1.00”, did the obvious check. Realized that was wrong, started to construct the algebraic equations in my head, but then realized I could do it iteratively (guess $1.01, check, guess $1.02, check…), then realized it would be quicker with successive approximation, then “guessed” $1.05, did the check and was done. The whole process took a few seconds and would have been faster if I hadn’t wasted time on the algebra.
A Royale with cheese.
How did you and they buy things in the old days when everything used to cost a nickel? Ask any old person and they’ll tell you how you could buy anything with a nickel;, a hamburger cost a nickel, a bottle of beer cost a nickel, a car cost a nickel… It was the only unit of currency back then. Some people are so old they can remember when you could buy a dollar for a nickel.
A method I’ve found helpful for the “missing dollar” problem is to find 30 objects to represent the dollars, and to go through the story with those objects. There’s no missing object at the end, so there’s no missing dollar.
In those days, nickels had pictures of bumblebees on 'em. “Give me five bees for a quarter,” you’d say.
Now if you had 10 philosophers in a room, then the ice cream would melt whilst they pondered the question. 
More precise wording would have been “Go up a hill 30 MPH and back down the same hill at 60MPH.” Which I think everybody would assume anyway.
This is actually a very practical calculation for pilots and boat captains, where this effect comes into play with winds aloft and water currents/river flow.
And tried to figure out whose chopsticks to use.
I’ve always felt these sorts of problems are sketchy and annoying, not because they test your arithmetic ability, but because they’re testing your ability to parse out the deceptive part inherent in the way it’s phrased.
I mean, the whole thing hinges on realizing that “The expensive pencil costs $1.00 more than the cheap pencil” means that a ten cent cheap pencil and a $1 expensive pencil actually means that the expensive pencil is only 90 cents more than the cheap pencil, and that the actual equation is: (1 + x) + x = 1.10, where x is the cost of the cheap pencil.
The whole thing hinges on the “more than”- most people read it as something more like “The expensive pencil costs $1.00, more than the cost of the cheap pencil (and the total is $1.10)”, where the “more than” is more of an adjective describing that the expensive pencil costs more than the cheap one. It doesn’t make a lot of sense, I know, but that’s the point- if you don’t read carefully and think about what it’s actually saying.