A friend comes to other and says can u do me a favour pick letters randomly from the stack such that all the letters that u pick are 5% of the total letters. The other friend while sorting just picked up letter number one, missed one, picked up another letter, missed two picked one letter ,missed three, picked another letter, and so on...till he picked last letter to his amazement he found that the picked up letters were 5% of the total letters in the stack. How many letters did he pick?
RE: A friend comes to other and says can u do me a
Let the total number of cards removed be n thus the total number of cards in the pack is sum of series (1 2 3 ..n).Sum of this series is (n)(n-1)/2. thus equating (we know cards removed is 5 of total cards)we get n 39.
RE: A friend comes to other and says can u do me a
ans - 39 total cards - 1 2 3 4 5 6 7 8 9 10....no of cards picked - 1 2 3 4....so total no of cards n (n+1) where n is no of cards picked ---------- 2then 5 of total no of cards [n(n+1)/2] [5/100] n so n 39
