NCERT Class 9 Solutions: Surface Areas and Volumes (Chapter 13) Exercise 13.6 – Part 1
Q1 The circumference of the base of a cylindrical vessel is and its height is . How many liters of water can it hold? ( )
Solution:

Let, the radius of the cylindrical vessel be

Height (h) of vessel

Circumference of vessel
We know that, circumference of the base of the cylindrical vessel
Therefore, capacity of the cylindrical vessel




(Since, )

Therefore, vessel can hold liters of water.
Q2 The inner diameter of a cylindrical wooden pipe is and its outer diameter is . The length of pipe is . Find the mass of the pipe, if of wood has a mass of .
Solution:

Inner diameter

Therefore, inner radius (r) =

Outer diameter

Therefore, outer radius(R)

Outer volume

Inner volume
Since the inner volume is empty, volume of the wood used = outer volume  inner volume
Since, of wood has a mass of , therefore mass of the pipe =