Question

If 6 more white balls are put in the 'box. The probability of drawing a white ball will be double than that in (i). Find x

• A. 6
• B. 5
• C. 4
• D. 3

Answer 1

Answer: (D)

3

Total number of balls when 6 more white balls are put in the box = 12 + 6 = 18
Number of white ball = x + 6
Now According to problem,
P (drawing a white ball) = 2 P (drawing a white ball in case i)
$\Rightarrow \frac{x+6}{18}=2\left(\frac{x}{12}\right)$
$\Rightarrow \frac{x+6}{18}=\frac{x}{6}$
$\Rightarrow x+6=3x$
$\Rightarrow 2x=6$
$\Rightarrow x=3$