Question

there are 12 identical balls of different colours in a bag . If 6 more black balls are added the probability of drawing black balls increases by 1/12. Find the original number of black balls.​

Answer 1

Answer:

9 balls.

Step-by-step explanation:

Let the original number of black balls be x.

Probability of drawing a black ball initially = x/12

Now, New number of balls = 12+6

Total number of black balls = x+6

Therefore, New probability = x+6/18

x+6/18 - x/12 = 1/12

=> (2(x+6) - 3x)/36 = 1/12

=> 12 - x = 3

=> x = 9