Question

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.

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Answer 1

Step-by-step explanation:

Total number of balls in the bag = 12

Number of black balls in the box = x

$probability \: of \: getting \: a \: black \: ball = \frac{number \: of \: black \: balls}{total \: number \: of \: balls} \\ \frac{x}{12}$

hope it helps

Answer 2

Answer:

3

Step-by-step explanation:

Initially, total number of balls =12

No. of black balls =x

So, P(black ball) =

12

x

If 6 more black balls are added, total number of balls =12+6=18

NO. of black balls =x+6

P(black ball) =

18

x+6

Given the probability of drawing a black ball is now double of what it was before

So,

12

2x

=

18

(x+6)

6

x

=

18

(x+6)

3x=x+6

2x=6

x=3

So, the number of black balls present initially =3.

Hope it helps.