Question

I know the answer is 4 but can someone show me how that was found?
A random draw is being designed for 210 participants. A single winner is to be chosen, and all the participants must have an equal probability of winning. If the winner is to be drawn using 10 balls numbered 0 through 9, how many balls need to be picked, regardless of order, so that each of the 210 participants can be assigned a unique set of numbers?

Answer 1

It sounds like we choose n balls out of 10 (and we don't know n)

there 10 Choose n combinations
we want this to be 210 or bigger, so each person gets a unique combination
\[\left(\begin{matrix}10 \\ n\end{matrix}\right)≥210\]

Answer 2

off-hand, I don't know how to "solve" for n other than trying some numbers and see what is the smallest n the works.

Answer 3

Im so confused. I just found out the answer isn't 4 it is either 5 or 6. But I can't fiqure out how those numbers make sense.

Answer 4

The question is not very clear. What they are doing is a bit mysterious... one of those goofy questions where only the asker (maybe) has an idea of what they want.

Answer 5

lol watch when I fiquired it out it will be something so simple. Or maybe not. :P

Answer 6

If you find out, please post the answer and explanation here. It helps me understand "goofy questions". Good luck.

Answer 7

thanks I will

Answer 8

thanks