Question

A jar contains $24$ marbles, some green and others 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 marbles in the jar.

• A. $12$
• B. $14$
• C. $8$
• D. $10$

Answer 1

Answer: (C)

A jar contains 24 marbles, some green and others blue. If a marble is drawn at random from the jar, the probability that it is green is $P\left(E\right)=\frac{2}{3}.$

Therefore probability of blue marble is$P\left(E^{\prime }\right)=1-P\left(E\right)$$=1-\frac{2}{3}.=\frac{1}{3}$

The total number of blue marbles=P(E')*total number of marbles=$\frac{1}{3}\ast 24=8$