Here's a puzzle I just heard and while I know that this reasoning is fundamentally wrong, I can't explain why:
- Three people bought a dish for, say, 25\$ and paid 30\$
- The waiter didn't want to divide 5 by 3, so he took 2\$ for himself and gave 1$ to each of the clients
- Each of them seems to have spent 9\$, but 9\$ x 3 = 27\$, not 28. What happened to this one dollar?
Expenditure of customers: $$ 30 \text{ (initial payment})-\color{green}{3} \text{ (change})=\color{teal}{27}. $$ Income of restaurant: $$ 30-\color{red}{2} \text{ (waiter's stolen amount})-\color{green}{3}\text{ (change to customers})=\color{blue}{25}. $$ Income of waiter: $$ \color{red}{2}, $$ which is just the amount he stole.
Total income $=\color{red}{2}+\color{blue}{25}=\color{teal}{27}=$ total expenditure. So no inconsistency here.