Question

A heap of rice is in the form of a cone of diameter $9$ m and height $3.5$ m. The volume of the rice is $74.25$ $m^3$. Canvas cloth required to just cover the heap is $80.62$ $m^2$.Write $1$ if true and $0$ if false.

Answer 1

Given, diameter $d=9m$.

Then, radius $r=\frac{9}{2}=4.5m$.

Also, height $h=3.5m$.

We know, volume of cone $=\frac{1}{3}\pi r^{2}h$

$=\frac{1}{3}\pi \left(4.5{)}^2\right(3.5)c{m}^3$ $=74.25c{m}^3$.

We know, $l^2=r^2+h^2$

$⟹$ $l^2=(4.5{)}^2+(3.5{)}^2=20.25+12.25=32.50$

$⟹l=5.7$.

Then, curved surface area $=\pi rl=\frac{22}{7}\left(5.7\right)\left(4.5\right)=80.62c{m}^2$.

That is, the given statement is true and $1$ is the answer.