Problem 3:
There is a basket in front of you that has $100$ balls numbered from $1$ to $100$ (each ball has a different number). You are asked to pick balls from this basket randomly without looking. After picking how many balls can you be sure that you have chosen at least one even-numbered ball?
BdMO National Primary 2011/3
"Inspiration is needed in geometry, just as much as in poetry." -- Aleksandr Pushkin
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atiab jobayer
- Posts:23
- Joined:Thu Dec 19, 2013 7:40 pm
Re: BdMO National Primary 2011/3
we know that there are 50 odd and 50even numbers in 1-100.after picking 50 balls randomly the 51 st number will be even number.( if the first 50 is odd or there will be a even number in the first fifty) 
math champion