Question

a box contains 12 balls out of X fore black if one ball is drawn at random from the box what is the probability that it will be black ball if 6 black balls are put in the box the probability of drawing a black ball is done double of what it was before find x​

Answer 1

Step-by-step explanation:

let x be the number of black balls

probability of black balls = x/12

case 1

if 6 more black balls are added then

number of black balls= x+ 6

total number of balls = 12+6=18

probability of black ball now = x+6/18

given that: x+6/18=2(x/12)

when we solve this we get

x=3