Question

A box contains 12 balls out of which are black. If one ball is drawn a random from the box, what is the probability that it will be a black ball.
if 6 more balls are put in box , probability of drawing black ball is now double of what it was before

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Answer 1

Answer:

x=3

Explanation:

Total number of balls = 18

Number of black balls = x + 6

P (drawing a black ball) = (x+6)/18

Therefore, we have:

x+6/18=2(x/12)

x+6/18=x/6

x+6=3x

3x-x=6

2x=6

x=3