5 ms·

The bug is obvious when they say "one envelope contains 2*A and the other A/2". Well no, one doesn't contain one fourth of the other.

• xmprt 4y ago
  That's not what it's saying. It's saying one envelope contains A and the other contains either 2*A or A/2.
  • qwertox 4y ago
    Yes, but doesn't the formula treat it a such?
  • davidguetta 4y ago
    yes but the formula at bullet point 7 says it. That's the point. The formula is wrong and doesn't correspond to reality
• mike_hock 4y ago
  Basically the sleight of hand trick is using a random variable A as though it was a constant. Yes, B = A/2 or B = 2A with probability .5 each, but not for the same value of A.
  • rawling 4y ago
    Why not?
    • Tepix 4y ago
      A is the starting value, in the one case it's half as much as in the other case.