Question

A bag contains 18 balls out of which x are red. if one ball is drawn at random from the bag, what is the probabilitythat it is red

if 2 more red ball are put in the bag the probablity of drawing a red ball will be 9/8 time the probablity of drawing a red ball in the first case .find the value of x​

Answer 1

No. of red balls in the bag = x

Total balls = 18

$P(e)= \frac{ No. \: of favourable \: Outcomes}{total \: outcomes}$

= x/18

Now, 2 more balls are added to the bag that are red so the bag contains 20 balls out of which (x + 2) balls are red

By question,

9/8 * x/18 = (x+2)/20

x/16 = (x+2)/20

x/4 = (x+2)/5

5x = 4x + 8

$x \: = 8$