Question

In a box there are equal number of blue and red pens. If only half of the red pens are defective, what fraction of the pens are not defective?

• A. $\frac{1}{2}$
• B. $\frac{1}{3}$
• C. $\frac{1}{4}$
• D. $\frac{3}{4}$

Answer 1

The correct option is D $\frac{3}{4}$

There are equal number of red and blue pens, so the fraction of red pens = $\frac{1}{2}$
Half of the red pens are defective.
It means half of $\frac{1}{2}$ of the total number of pens are defective.
Therefore, the fraction of pens which are defective = $\frac{1}{4}$
It means one quarter of the total number of pens are defective.
We know that 4 quarters make a whole.
Therefore, the fraction of pens which are not defective = Three quarters of the total number of pens.
Three quarters can be represented in the fraction form as $\frac{3}{4}$.
So, $\frac{3}{4}$ of the total number of pens are not defective.