The radii of three concentric circles are in the ratio of 4 : 5 : 7. What is the ratio of the area between the two inner circles to that between the two outer circles?

If the ratio of the areas of two similar triangle ABC and DEF is 36:81 and EF = 6.9 cm., then BC is equal to –

A conical vessel whose internal base radius is 18 cm and height 60 cm is full of a liquid. The entire liquid of the vessel is emptied into a cylindrical vessel with internal radius 15 cm. The height (in cm) to which the liquid rises in the cylindrical vessel is:

The diameter of a roller is 84 cm and its length is 120 cm. It makes 500 complete revolutions to move once over to level a playground. Find the area of the playground.

A right circular cone of largest volume is cut out from a solid wooden hemisphere. The remaining material is what percentage of the volume of the original hemisphere?

A straight line parallel to the base QR of the ∆PQR intersect PQ and PR at the points S and T respectively. If the area of the ∆PQT be 36 cm² then area of the ∆PRS is:

The diagonal of a square is equal to the side of an equilateral triangle. If the area of the square is $$ {18\sqrt{3}}$$ sq.cm. What is the area (in cm²) of the equilateral triangle ?

The diameter of a circle is equal to the perimeter of a square whose area is 3136 sq cm. What is the circumference of the circle?