Question

In a beg there are $6$ red ball and some blue balls. If an drawing one ball the probability of drawing a ball is thrice of drawing a red ball, find the number of blue balls in the beg.

Answer 1

Let the no. of blue balls be $x$

Total no. of balls $=6+x$

Also given that,

Probability of blue ball $=3\times$ Prbability of red ball

$\therefore \frac{x}{6+x}=\frac{3\times 6}{6+x}$

$\Rightarrow x=18$

Hence there are $18$ blue balls in the bag.