The ratio between the areas of two circles is $4: 7.$ What will be the ratio of their radii?

If every side of a triangle is doubled,the area of the new triangle is $K$ times the area of the old one. $K$ is equal to

The length of a rectangle is increased by $33.33 \%$. By what percent should the width be decreased to maintain the same area? (in $\%$)

$A$ circular swimming pool is surrounded by a concrete wall $4 \ m$ wide. If the area of the concrete wall surrounding the pool is $11/25$ that of the pool,then the radius (in $m$) of the pool is

$A$ circular wire of diameter $112 \, cm$ is cut and bent in the form of a rectangle whose sides are in the ratio of $9:7$. The small side of the rectangle is......$cm$.

$A$ park square in shape has a $3 \, m$ wide road inside it running along its sides. The area occupied by the road is $1764 \, m^{2}$. What is the perimeter along the outer edge of the road? (in $metres$)