A box contains 12 balls out of which x are black. If one ball is drawn at random from the box, what is the probability that it will be a black ball? If 6 more black balls are put in the box, the probability of drawing a black ball is now double of what it was before. Find x.
Total number of possible outcome(s) are 16 i.e., n(S) = 16
Let A be the favourable outcomes of getting getting a number which is perfect square. Then A = (9,16) i.e., n(A) = 2
Therefore,