Question

What fraction of an hour is $15$ minutes? The diameter of a circle is $26cm$. Find its radius.

Answer 1

Hint: First, we need to know about the concept of the hours to minutes and also diameter to radius relationship to solve the given problem.
Since we know that the one hour can be measured in the minutes as sixty minutes which expressed as $1h = 60\min $
Also, the relation between the radius and the diameter is $d = 2r$, where the diameter is two times of the given radius.

Complete step by step answer:
Given that, what fraction of an hour is $15$ minutes. We know that $1h = 60\min $ and then we will make use of the conversion method, that is $1\min = \dfrac{1}{{60}}h$ (dividing both sides by the number sixty)
Thus, to find the fifteen minutes in one hour, we will multiply the converted value into the number fifteen. Hence, we get $15\min = 15 \times \dfrac{1}{{60}}h$
Thus, using the division, we get $15\min = \dfrac{1}{4}h$ and it can be written as in the decimal form as $4\left| \!{\overline {\,
 1 \,}} \right. = 0.25$
Therefore, the one hour in $15$ minutes is $0.25h= \dfrac{1}{4}$

The diameter of a circle is $26cm$. Find its radius.
Since the diameter is the calculation of the distance between two points on a circle passing through the circle. Hence the diameter of the circle is $2$ times its radius
Hence the formula to find the radius is given $d = 2r \Rightarrow r = \dfrac{d}{2}$ where the diameter is given as $26cm$ and hence we get the radius as $r = \dfrac{{26cm}}{2}$ and using division we have $r = 13cm$ is the radius of the given diameter.

Note:
Now first of all let us understand the circle of the diameter and radius. So, a circle is the collection of all the points lying in a plane at a distance from the center point. The distance between the center and all the points on the circle is known as the radius.
Hence the distance between two points on the circle passing from the center is known as the diameter of the circle.
Therefore, the diameter is double in length to the radius, and hence we have the relation as $d = 2r$