Question

A jar contains $24$ marbles, some are green and others are blue. If a marble is drawn at random from the jar, the probability that it is green is $\frac{2}{3}$. Find the number of blue balls in the jar.

Answer 1

Total number of marbles$=24$

Let the number of green marbles$=x$

So, the number of blue marbles$=24-x$

Probability of green marble$=\frac{x}{24}$

According to the question,

$\frac{x}{24}=\frac{2}{3}\Rightarrow x=\frac{2\times 24}{3}\Rightarrow x=16$

Number of blue marbles$24-x=24-16=8$

Hence, the number of blue balls in the jar is $8$