This puzzle just appeared on Quora and has a vaguely similar vibe:

"The woman in front of you places two envelopes onto the table. One is labeled Envelope A, and one is labeled Envelope B.

“Here’s the deal,” she says. “Each of these envelopes contains a significant sum of cash. One of them contains exactly twice as much money as the other.”

You nod eagerly, excited to see where this is going.

“You can keep one envelope, and I’ll keep the other one,” she says. “The decision is yours. But you’re only allowed to look inside one of them before you decide which one you want.”

You take envelope A, open it and count the money inside.

“Now,” she says, “do you want to keep Envelope A, or do you want to switch to Envelope B?”

Here’s the dilemma: No matter which envelope you’re holding, your expected value is always higher if you switch.

Let’s say you looked inside Envelope A, and found $1,000. You know that one envelope contains twice as much money as the other, but you don’t know which envelope has more. That means there’s a 50% chance that Envelope B contains $2,000, and a 50% chance that it only contains $500.

So let’s say you give up Envelope A and take Envelope B instead. If B is the better envelope, then you’ll gain $1,000. And if B is the poorer envelope, then you’ll only lose $500.

That means that if you switch, there’s an equal chance that you’ll gain $1,000 or lose $500. Seems like a good deal, right? Your expected gain is higher than your expected loss, so if your goal is to go home with as much money as possible, it makes sense to switch envelopes.

But once you’re holding Envelope B, the same logic applies. If the amount of money in Envelope B is X dollars, then by switching back for Envelope A, you know you’ll either gain X dollars or lose X/2 dollars. So once again, it makes sense to switch envelopes.

Does that make sense?