# Ex.11.3 Q16 Perimeter and Area - NCERT Maths Class 7

Go back to  'Ex.11.3'

## Question

How many times a wheel of radius $$28 \rm\,cm$$ must rotate to go $$352 \rm\,m$$? \begin{align}\left( {{\text{Take }}\pi = \frac{{22}}{7}} \right)\end{align}

Video Solution
Perimeter And Area
Ex 11.3 | Question 16

## Text Solution

What is known?

A wheel of $$28 \rm\,cm$$.

What is unknown?

Number of times the given wheel must rotate to go $$352 \rm\,m$$.

Reasoning:

The distance covered by the wheel in one revolution is equal to the circumference of the wheel. Now, to find out the number of times wheel should rotate, divide the total distance covered by the circumference of the wheel.

Steps:

Radius of wheel $$=$$ $$28 \rm\,cm$$

Circumference of wheel

\begin{align} &= 2\pi r \\ &= 2 \times \frac{{22}}{7} \times 28\\ &= 2 \times 22 \times 4\\ &= 176\;\rm\,cm\end{align}

Total distance $$=$$ $$352 \rm\,m$$ $$= 35200 \rm\,cm$$

No of times wheel should rotate

\begin{align} &= \frac{\text{Total distance covered by wheel}}{\text{Circumference of the wheel}}\\&= \frac{{35200}}{{176}}\\&= 200\end{align}

Therefore, wheel must rotate $$200$$ times to go $$352 \rm\,m$$.

Learn from the best math teachers and top your exams

• Live one on one classroom and doubt clearing
• Practice worksheets in and after class for conceptual clarity
• Personalized curriculum to keep up with school