A solid sphere of radius 3 cm is melted to form a hollow right circular cylindrical tube of length 4 cm and external radius 5 cm. The thickness of the tube is
The ratio of curved surface area and volume of a cylinder is 1 : 7. The ratio of total surface area and volume is 187 : 770. What is the respective ratio of its base radius and height?
Rehman goes on a trip on his motor-cycle and rides for 661 kms. If he rides for 8 hours at a speed of 31 km/hr, find at what speed he travels for the remaining 7 hours of the journey?