Question

5) A bag contains 12 balls out of which x are white. If one ball is taken out from the bag, find the prabability of getting a white ball. If 6 more white balls are added to the bag and the probability now for getting a white ball is double the previous one, find the value of x.

Answer 1

first probability of white balls=x/12
6 white balls added
now white balls=x+6
total=12+6=18
now probability=x+6/18

it is given double the probability of previous one
so (x/12)*2=2x/24

(x+6)/18=2x/24
24x+144=36x
144=12x
x=12
plzz check the answer

Answer 2

Bag contains 12 balls.
x are white balls.
P[of getting white balls]=x 
                                         12
6 more white balls are added. 
Total balls are 18 and white balls are x+6.
P[of getting white ball after]=2·P[of getting white balls before]
(x+6)/18=2·(x/12)
By dividing,
(x+6)/3=x
x+6=3x
3x-x=6
2x=6
x=3