Let’s do some math



Alice secretly picks two different real numbers by an unknown process and puts them in two (abstract) envelopes.  Bob chooses one of the two envelopes randomly (with a fair coin toss), and shows you the number in that envelope.  You must now guess whether the number in the other, closed envelope is larger or smaller than the one you’ve seen.

Is there a strategy which gives you a better than 50% chance of guessing correctly, no matter what procedure Alice used to pick her numbers?

A nice conundrum.

Think hard before you read the solution.

(Hat tip: Irsal Mashhor — thanks bro.)


4 Responses to Let’s do some math

  1. samah says:

    Ok cuba. Kalau experiment multiple times, kita boleh tgk history. Averaged out over time Bob must have chosen 50% smaller, 50% larger.

    So given up to the current run the history all this while is 48% smaller, 52% larger, then the next time Bob chooses, it is more likely for him to choose a smaller number?

    Cara Alice pilih number has no effect,

  2. samah says:

    dem patut aa asyik kalah judi cis

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