# Ex.13.6 Q1 Surface Areas and Volumes Solution - NCERT Maths Class 9

## Question

The circumference of the base of a cylindrical vessel is \(132\; cm\) and its height is \(25\; cm\). How many litres of water can it hold? \(\begin{align}(1000\,c{m^3} = 1\,l) \end{align}\)

## Text Solution

**Reasoning:**

Volume of a cylinder of base radius \(r\) and height is \(V = \pi r^{2} h\).

**What is known?**

Circumference of the base and the height.

**What is unknown?**

Litres of water the cylindrical vessel can hold.

**Steps:**

Since the base of a cylindrical vessel is a circle, the circumference is \(2 \pi r=132 \mathrm{cm}\) (given)

\(\begin{align} 2\pi r &= 132\\2 \times \frac{{22}}{7} \times r &= 132\\r &= \frac{{132 \times 7}}{{2 \times 22}}\\ &= 21\,\,cm \end{align}\)

Radius \(\begin{align}(r) = 21\, \rm{cm} \end{align}\)

Height \(\begin{align}(h) = 25\, \rm{cm}\end{align}\)

Capacity of the cylindrical vessel \(=\) Volume of the cylindrical vessel \( =𝜋𝑟^2ℎ\)

\(\begin{align}&= \frac{{22}}{7} \times 21 \times 21 \times 25 \\&= 34650\,c{m^3} \end{align}\)

Answer should be in litres

\(\begin{align} 1000\,c{m^3} &= 1\,\,l\\34650\,c{m^3} &= x\,\,l\\x &= \frac{{34650}}{{1000}}\\& = 34.65\,l \end{align}\)

**Answer:**

Capacity of the cylindrical vessel\(\begin{align}= 34.65\,l \end{align}\)