Question

Which of the following fractions is not in its lowest form?

• A. $\frac{7}{5}$
• B. $\frac{15}{20}$
• C. $\frac{13}{33}$
• D. $\frac{27}{28}$

Answer 1

The correct option is B $\frac{15}{20}$

We know that a fraction is in its lowest form if the HCF of its numerator and denominator is 1.

• Consider $\frac{7}{5}$.

HCF of 7 and 5 is 1. The fraction cannot be simplified further. So, it is in its lowest form.

• Consider $\frac{15}{20}$.

HCF of 15 and 20 is 5. The fraction
can be simplified further as
$\frac{15÷5}{20÷5}=\frac{3}{4}$
So, it is not in its lowest form.

• Consider $\frac{13}{33}$.

HCF of 13 and 33 is 1. The fraction cannot be simplified further. So, it is in its lowest form.

• Consider $\frac{27}{28}$.

HCF of 27 and 28 is 1. The fraction cannot be simplified further. So, it is in its lowest form.

Hence, $\frac{15}{20}$ is not in its lowest form.