Silent_Mo

I think, before, he had 20% to share with the singer to whom he gives 5%, leaving 15% (and not 0.15%) for himself. Now he got 50% to share with the singer to whom he gives 5%, leaving 45% (instead of 4.5%) for himself. And 45 is indeed 3 times 15 (now the math adds up).

You have 3 ways to get the deduction : you get it on the first try, the second try or the third and last try. You have 10% chances to succeed on the first try. You have 10% chances to succeed on the second try if you failed the first one. So you first count 90% for the first fail and then the 10% of the success on the second try, so 9% chances to succeed. Idem for the success on the third try but with two fail, so 90% * 90% * 10% or 8.1%. In the end you have 27.1% chances of success. The other way to get to this result is to see that the only way to fail the deduction is to fail three times in a row so 90% * 90% * 90%, so 72.9% (0.9^3=0.729). If this is the probability to fail than the probability to succeed is 100% - 72.9% = 27.1%. Anyway, not 30% (not too far but not 30%). Ok, I am done doing maths this month, bye 😉