Prakash Tiwari and Ishita Joshi Solutions for Chapter: Mensuration, Exercise 7: Let's Practice

Find the area and circumference of the following circles whose:

$d=21 \text{cm}$

Find the area and circumference of the following circles whose:

$r=10.5 \text{m}$

Find the area and circumference of the following circles whose:

$d=4 \text{cm }\left(\text{use} \pi =3.14\right)$

How many times a wheel of radius $35 \mathrm{m}$ must rotate to go $1 \mathrm{km} 320 \mathrm{m}$.

The seconds hand of a circular clock is $19 \mathrm{cm}$ long. How far does the tip of the minute hand move in half an hour? (consider $\mathrm{\pi } = 3.14$)
 

A circular field is fenced with a fencing wire of length $396 \mathrm{m}$. The farmer wants to plant flower saplings in the garden which costs $50$ paise each. How much amount should he spend on the saplings, if he can plant $5$ saplings in $1 \mathrm{m}².$

 A circle of radius $3 \mathrm{cm}$ is cut out from a rectangular sheet of paper of dimensions $10\mathrm{cm} \times 11\mathrm{cm}$. What is the area of the leftover sheet of paper? (consider $\mathrm{\pi } = 3.14$)

From a circular sheet of paper of radius $21 \mathrm{cm}$, three circles of radius $1.4 \mathrm{cm}$ and a square of side $5 \mathrm{cm}$ are cut out. Find the area of remaining sheet of paper.