Two Envelopes Naive Expected Value

Problem

The two-envelope puzzle: after seeing amount in one envelope, the naive argument says the other holds 2 * amount or amount / 2 with equal probability, giving a switch expected value of 1.25 * amount.

Return [keep_value, naive_switch_value] = [amount, 1.25 * amount].

Hint

The naive calculation ignores that the amount you saw changes the distribution of what is in the other envelope.

Test cases

case 1

in: [10]

expected: [10,12.5]

case 2

in: [0]

expected: [0,0]

case 3

in: [8]

expected: [8,10]

Starter codePython

def two_envelope_naive_ev(amount):
    # Your code here
    pass

3 test cases · run your code against them in the editor