Question

@aajugdar 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?

A. 10

B. 6

C. 5

D. 4

Answer 1

10 balls and 210 participants
and order doesnt matter
so you use combination

Answer 2

suppose the number of balls needed to be picked is n
so 10 C_n = 210

Answer 3

so 10! /n!(10-n)! = 210

Answer 4

@BSwan idk how to solve this :P

Answer 5

just put the values
and see which one matches

Answer 6

its not 10

Answer 7

so 6,5 or 4

Answer 8

i think its 4 but idk the method on how to get it

Answer 9

for 6 and 4 it would give same result?

Answer 10

well @aajugdar this question is more like CS :P
in some how its asking
for any number u can express it by balls
so number from 0 to 210
0
1
2
... 210
how many ball do u need :)

Answer 11

like how many digits u can pick lol

Answer 12

okay?

Answer 13

check this if it gives u a hint
0000
0001
0002
0003
...
0123
0138
...
are u getting it ?

Answer 14

im not lml

Answer 15

well if u just put 4 in equation u will get 210 .-. but even for 6 you get the same so how do you say its 4 and not 6 @BSwan

Answer 16

well the min number is
3 , cuz 2,1,0
since its not there its ok for one digit
4 , then 0,2,1,0
u can take 5
00210...
u can take how many balles >=3
it will be unique but its better to take the min

Answer 17

so its 4 then?

Answer 18

oh cool ^^

Answer 19

yes

Answer 20

see its more like CS :P

Answer 21

I'll put in 4 and see if its right

Answer 22

4 was wrong ;((

Answer 23

.-. what?

Answer 24

grrr why :O

Answer 25

so whats the answer?

Answer 26

idkk. maybe it was 6

Answer 27

If you get it wrong it just gives you an X and says incorrect

Answer 28

yess it 6