Question

In a purse there are 30 coins, twenty one-rupee and remaining 50-paise coins. Eleven coins are picked simultaneously at random and are placed in a box. If a coin is now picked from the box, find the probability of it being a rupee coin?
Option 1 : 4/7 Option 2 : 1/2 Option 3 : 2/3 Option 4 : 5/6

Answer 1

hmm 21 rupee or 20 one-rupee?

Answer 2

`one-rupee` = `100-paise`

Answer 3

20 one rupee

Answer 4

this looks like committees and subcommittees problem hmm

Answer 5

probability of picking 11 coins from 30 is

Answer 6

probability of picking one coin from 11 coins is

Answer 7

11C1
Is a formula to determine the many ways you can choose 1 out of 11 coins which would be 11 ...its abt combinations
So I dont think its fair to say that 11C1 is the probability of choosing 1 coin from 11

Answer 8

Im not sure how to approach this problem though
I bet @ganeshie8 has got smth up his sleeve

Answer 9

no this looks hard !
lets try @dan815

Answer 10

@Kainui ...........

Answer 11

dan 20/30

Answer 12

oh sry

Answer 13

no that doesnt work there isnt a 20/30 chance on each picking so

Answer 14

answer is 2/3

Answer 15

-,-

Answer 16

ok makes sense

Answer 17

but i donno how to solve

Answer 18

when u pick 11 coins, there is 2/3 chance that in the box u have 1 : 0.5 rupee ratio

Answer 19

if u considering multiple picks