A circle is divided into certain number of equal parts. If 15 of the parts so formed represent the fraction $ \frac{3}{5}, $ the number of parts in which the circle has been divided is(1) 45
(2) 75
(3) 20
(4) 25

Given:

A circle is divided into certain number of equal parts.

15 of the parts so formed represent the fraction \( \frac{3}{5} \).
To do:

We have to find the number of parts in which the circle has been divided.

Solution:

Let the number of parts in which the circle has been divided be $x$.

This implies,

$\frac{15}{x}=\frac{3}{5}$

$15\times5=3\times x$   (On cross multiplication)

$75=3x$

$x=\frac{75}{3}$

$x=25$

Therefore, the circle is divided into 25 parts.