Question

An urn 6 blue and x green balls. If the probability of drawing a green ball is double that of drawing a blue ball, then x = _________.

Answer 1

Total number of balls = 6 + x

Probability of drawing a green ball = $\frac{x}{x+6}$

Probability of drawing a blue ball = $\frac{6}{x+6}$

It is given that,

Probability of drawing a green ball = 2 × Probability of drawing a blue ball

$$\begin{gathered} \Rightarrow \frac{x}{x+6}=2\times \frac{6}{x+6} \\ \Rightarrow x=12 \end{gathered}$$

An urn 6 blue and x green balls. If the probability of drawing a green ball is double that of drawing a blue ball, then x = ___12___.