CBSE Class 10-Mathematics: Chapter –13 Surface Areas and Volumes Part 20
Doorsteptutor material for CBSE is prepared by world's top subject experts: fully solved questions with step-by-step explanation- practice your way to success.
Question 17:
The radius of the base and the height of solid right cylinder are in the ratio and its volume is . Find the total surface area of the cylinder.
Answer:
Let r be the radius of the base and h be the height of the solid right circular cylinder.
Volume of the cylinder
Surface area of cylinder
Question 18:
A toy is in form of a cone mounted on a hemisphere of common base radius 7 cm. The total height of the toy is , find the total surface area of the toy.
Answer:
Total surface area of . of hemisphere . of cone
Here,
T.S.A. of
Question 19:
A well in diameter and deep be dug in rectangular field by . The earth taken out is spread evenly on the field. Find the level of the earth raised in the field.
Answer:
Radius of well
Depth of well
Volume of earth taken out
Area of field excluding well
Level of earth raised
Question 20:
A solid sphere of radius is melted into a hollow cylinder of uniform thickness. If the external radius of the base of cylinder is and its height is , find the uniform thickness of the cylinder.
Answer:
Volume of sphere
Let the internal radius of cylinder
External radius
Volume
Volume of the hollow cylinder Volume of sphere