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

The area of the circumcircle of an equilateral triangle is $3 \pi \, cm^2$. The perimeter of the triangle is

$A$ hollow spherical shell is made of a metal of density $4.9 \, g/cm^3$. If its internal and external radii are $10 \, cm$ and $12 \, cm$ respectively,find the weight of the shell. (Take $\pi = 3.1416$) (in $gm$)

$A$ lawn is in the shape of a rectangle of length $60 \ m$ and width $40 \ m$. Inside the lawn,there is a footpath of uniform width $1 \ m$ bordering the lawn. The area of the path is ....... $m^2$.

The perimeter of a square is equal to twice the perimeter of a rectangle of length $8\, cm$ and breadth $7\, cm$. What is the circumference of a semicircle whose diameter is equal to the side of the square? (rounded off to the two decimal places) (in $cm$)

$A$ plot of land is in the shape of a right-angled isosceles triangle. The length of the hypotenuse is $50 \sqrt{2} \text{ m}$. The cost of fencing is ₹$3$ per metre. The total cost of fencing the plot will be