$A$ rectangle has width $a$ and length $b$. If the width is decreased by $20 \%$ and the length is increased by $10 \%$,what is the area of the new rectangle as a percentage of the original area $ab$?

The area of a circle is increased by $22\, cm^{2}$ when its radius is increased by $1\, cm$. The original radius of the circle is.......$cm$.

The area of a parallelogram is $240 \, cm^{2}$ and its height is $12 \, cm$. The base of the parallelogram is ........ $cm$.

The length of a plot is double its width. If a square piece of land of area $150 \, m^2$ occupies $\frac{1}{3}$ area of the plot,then what is the length of the plot? (in $m$)

How many metres of cloth $5\, m$ wide will be required to make a conical tent,the radius of whose base is $7\, m$ and height is $24\, m ?$ (in $m$)

$A$ room is $7 \text{ m}$ long and $5 \text{ m}$ broad. The doors and windows occupy $5 \text{ m}^2$. The cost of papering the remaining part of the walls with paper $75 \text{ cm}$ wide,at ₹ $4.20$ per piece of $13 \text{ m}$ length,is ₹ $39.20$. Find the height of the room in $\text{cm}$.