Alka Tuli and Rajesh Hassija Solutions for Chapter: Perimeter and Area, Exercise 8: MENTAL MATHS

The area of a square is $144 {\mathrm{m}}^2$. If the length of its side is $k$ metres, then find the value of $k$. 

Find the width of the cardboard, if its area is $52 \mathrm{sq}.\mathrm{cm}$and its length is $13 \mathrm{cm}$.

Find the radius of a circle whose circumference is $22\mathrm{\pi }$. (Take $\mathrm{\pi }=\frac{22}{7}$)

If the base of a triangle is twice its altitude and the altitude is $2\mathrm{x}$, then the area of the triangle is $4x^k$. Find the value of $k$.

The area of a parallelogram with side $12 \mathrm{cm}$ is $96 {\mathrm{cm}}^2$. If the length of its altitude is $k \mathrm{cm}$, find the value of $k$.

The ratio of the circumferences of two circles $2:5$. Find the ratio of their areas.

The area of a triangular field is $1.5 \mathrm{hectares}$. If the altitude is $300 \mathrm{m}$, find the corresponding base.

The width of a circular track with outer circumference $264 \mathrm{m}$ and inner circumference $220 \mathrm{m}$ is $k m$. Find the value of $k$.