Question

In a bag of marbles, $\frac{1}{2}$ of the marbles are red, $\frac{1}{4}$ of them are green, and $\frac{1}{5}$ of them are blue. If the remaining $2$ marbles are white, what is the number of green marbles in the bag?

• A. $4$
• B. $5$
• C. $8$
• D. $10$
• E. $40$

Answer 1

The correct option is D $10$

The fraction of white marbles is $1-(\frac{1}{2}+\frac{1}{4}+\frac{1}{5})=1-\frac{19}{20}=\frac{1}{20}$,
Let $x$ be total number of marbles, number of white marbles is $\frac{x}{20}$ which is equal to $2$.

Therefore, we get $x=40$.
Therefore, number of green marbles is equal to $\frac{1}{4}\times 40=10$.