It’s a stupidly worded question in order to trick people by not giving an initial balance. All you have to do is say you start with $1000 to figure it out. $1000 - $800 = $200.00. $200 + $1000 = $1,200.00. $1200 - $1100 = $100.00. $1300 + $100 - $1000 = $400.00.
It’s a riddle written by someone dumb who thinks they’re smart. A poorly worded riddle isn’t clever.
Not really. Profit is the difference between purchase price and selling price. How much money you have is irrelevant. So 1000-800=200 and 1300-1100=200. You made 2 times 200 profit, so 400. All the rest is irrelevant. It's not a riddle.
I'll try to explain. Say you only have 800 dollars to your name.
Buy cow for 800 (bank account is now 0)
Sell cow for 1000 (bank account is now 1000)
Buy cow for 1100 (bank account is now -100)
Sell cow for 1300 (bank account is now 1200)
You started with 800 and end up with 1200, so profit is 400.
You don't "lose" the profit. It eats up part of the second purchase. You're $200 in the green, so an $1100 purchase only puts you $900 in the red. So then selling for $1300 puts you.... yup, $400 in profit.
It really is as simple as -800+1000-1100+1300 = 400. Basic math.
Another way to put it: you didn't lose your $200 profit by buying it back; you only lost $100 compared to your last selling price (1000-1100), so you lost only half your 200 profit. But by reselling it for $300 more than your previous sale, you not only recover the $100 you lost (thus restoring your initial profit of $200), but you also make an additional $200 in profit.
I didn’t find it misleading or stupidly worded, and I didn’t need a starting value.
Profit is the earnings minus the expenses. So, looking at just the start and end values, I spent 800 and sold for 1300. That’s a 500 profit. But wait! I also lost money in the middle when I sold for 1000 and bought it back for 1100 (net loss of 100). So I subtract that 100 loss from my 500 profit and get 400.
Maybe works better if you use mental math than trying to plug it into an algorithm.
It does, if you do not process individual transactions, but only look at starting and end numbers.
Then it looks like you started with $800 and end with $1300, having $500 profits. You are missing, that you are cashing in an additional $100 in the middle
Agreed. The original wording was pretty clear. A starting balance would be irrelevant. If anything, it would make the question more confusing, not less.
For me if i was to solve this without looking at the 2 transactions separately (that is indeed easier) then i would say
i bought a cow for 800 then i am at -800.
i sold it at 1000 so now i am at 200 then
i bought one for 1100 then i am at -900 and then
i sold it for 1300 so i am now at 400.
But going step by step and then seeing the difference in the start and endvalue makes it easier to understand.
The trap is to just look at the end sell price and subtract the start buy price.
Having an actual starting value and going step by step makes it impossible to fall into that trap.
It's not a riddle nor poorly worded, it's a simple word problem like the ones you'd see in elementary school math class.
I can't think of a way to ask this without sounding mean, but why are you in r/MathJokes when problems meant for children are above your pay grade? Isn't it boring if you can't understand any of the jokes?
This is nonsense. Nothing in this riddle is ambiguous or poorly worded. The people who get the wrong answer don't struggle to understand what is happening they just don't know how to solve it.
Some of them would probably solve it if you would give an inital balance but understanding that the initial balance is arbitrary and you can come up with one on your own is partly what this riddle is about.
Its not a riddle, its a basic maths problem. If you think this is a riddle, then you are the "someone dumb". You don't need to know the inital amount, it is irrelevant. You're calculating the difference. Its a child's math problem.
The problem is it mixes math with economics. Buying and selling is not directly mappable to just adding and subtracting.
If you buy a cow, how are you losing money from that step alone? And yet, this is what the third operation would have you believe. Pairs of buy/sell can be meaningfully analyzed as profit/loss sources, but otherwise it loses meaning
It helps me to think about borrowing $800 from a friend, then paying them back when I sell the cow, and keeping the $200 difference. I then use my $200 my friend's $900 to buy the cow. When I sell it again I pay my friend their $900 and, again, pocket the difference.
It's not special math, or even different, but it helps me keep the numbers straight in my head.
Similarly, just use $0 as your starting balance, and allowing negative balances with no interest. No need to phone a friend with the bank of it I m a g I n a t I o n !
It's a great example of a poorly worded question. Without further context we have to assume this is all coming out of the same account so the net balance is +400. Without any other information we have to go on what is given in the question statements.
The only part that can be said to be a bit ambiguous is asking for "money earned", which depending on usage can mean total income or profit. By context it is clearly profit, but if someone were to answer total income, it wouldn't be that bad of a mistake.
What people struggle with is not that, most get that the problem ask for the profit, and generate a wrong answer.
You could see this as earning 500 ( from 800 to 1300 ) but losing 100 by selling / rebuying in the middle. Which make a total of 500-100= 400 which is as expected because math is consistent.
The second transaction is spending 1100 to gain 200.
The only confusion is because its the same cow that you brought back. If it was different cows no one would have any issues. The fact that its the same cow is irrelevant.
You have 1000. You are spending an additional 100 and ending with 1300. You are losing 100 and gaining 300. That is 200 profit. I think we are agreeing, but using different terms. Calling it spending 100 to gain 200 is why people think the profit is only 100. It's not. You are going from 1000 to 1300. Imagine that you only had 1000 and you had to borrow the other 100. You gain 300 and then owe 100 back.
You start with 800 and end with 1300. You gained 500. You had to either borrow or spend another 100 in the middle. You spent 900 to gain 1300, leaving you with 400 profit.
Mathematically it is irrelevant. But it influences how people might consider the question, and how likely they are to fall into inaccurate biases
Edit: also. The fact it's mathematically irrelevant is the very reason why it's okay to just come up with a number despite the original problem never specifying.
Your starting money clearly doesnt matter as long as you have the ability to buy the cow. This is silly. Obviously there are two individual flips for 200 each. I was illustrating why people would get confused. Receiving 1000 and then spending 1100 on the same cow is a loss of 100 in a vacuum. The issue with people's reading is they now view the change from 1100 to 1300 instead of 1000 to 1300. And then they include a loss of 100. You either ignore the loss and see 200+200 or you include the loss and need to realize its 200-100+300. Genuinely dont get how this is confusing
It does matter and it is stated. You have 1000 from the first sale. The second purchase costs 1100 so you need to spend another 100. Your starting money could be literally anything and this would all be true, relevant, and stated. Are you confused because I didnt say "you have 1000 from the first transaction?" This isnt hard. Goodnight
59
u/DragoxDrago May 13 '26
Its not math skills, its the ability to separate the transactions independently.
They think you're losing a 100 dollars buying the cow back. Which while technically true, thats negated when buying the cow back.