Question

Pavan built a conical flask using 550 $m^2$ of aluminium sheet. If the radius of the flask is 7 m, then how much water can be filled in the flask(in litres)? [The bottom of the flask is of another material.]

• A. 1232 litres
• B. 1232000 litres
• C. 12300 litres
• D. 123 litres

Answer 1

The correct option is B

1232000 litres

The area of aluminium sheet = Curved surface area of flask
$\Rightarrow 550m^2=\pi rl$
$\Rightarrow 550=\frac{22}{7}\times 7\times l$
$\Rightarrow 550=22l$
$\Rightarrow l=25m$

Now, height of flask
$\Rightarrow h=\sqrt{(l^2-r^2)}$
$\Rightarrow h=\sqrt{{25}^2-7^2}$
$\Rightarrow h=24m$

Hence, the volume of conical flask
$=\frac{1}{3}$ $\pi$$r^{2}h$
$=\frac{1}{3}\times \frac{22}{7}\times 7^2\times 24$
$=1232m^3$

We know that 1 m ${}^3=1000litres$

So, volume in litres $=1232000litres$