Question

What is the circumference of a 15-inch circle if the diameter of a circle is directly proportional to its radius and a circle with a 2-inch diameter has a circumference of approximately $6.28$ inches?

Answer 1

Hint: Here in this question we have been asked to find the circumference of a 15-inch circle using the concept in the question given as “the diameter of a circle is directly proportional to its radius and a circle with a 2-inch diameter has a circumference of approximately $6.28$ inches”.

Complete step-by-step answer:
Now considering the question we have been asked to find the circumference of a 15-inch circle.
Now considering from the information given in the question we know that the diameter of a circle is directly proportional to its radius.
We also know that if we consider a circle with 2-inch diameter it will have a circumference $6.28$ inches.
Therefore we can say that when the diameter is $d$ then the circumference will be given by

$\begin{align}
  & \Rightarrow \dfrac{c}{d}=\dfrac{6.28}{2} \\
 & \Rightarrow c=3.14d \\
\end{align}$ .
From the basic concepts of a circle we have learnt that the circumference of the circle is given as $2\pi r\Rightarrow \pi d$ and we also know that $\pi =3.14$ .
By using this concept we can say that the circumference of a 15-inch circle is given as $3.14\times 15=47.1$ inches.
Therefore we can conclude that the circumference of a 15-inch circle will be given as $47.1$ inches.

Note: While answering questions of this type we should clearly understand the given question otherwise we may get confused and can’t answer it exactly. Hence we should carefully understand the question so that someone can initially get confused with this question by seeing this long question and miss the exact point of what is asked.