ok, so, there's this soap called jackpot soap
where each bar has a bill in the middle, of different denominations

the breakdown is 52% $1, 26% $5, 13% $10, 6% $20, 2.9% $50, 0.1% $100
the question is:
How many bars of soap would customer have to buy so that, on average, she has purchased two containing a bill of at least $50 value?