Question

an open container made up of a metal sheet is in the form of a frustum of a cone of height 7cm with radii of its lower and upper circular ends as 4cm and 10cm respectively. Find the cost of oil which can completely fill the container at the rate of Rs 50 per litre.

Answer 1

Answer: The cost of oil which can completely fill the container at the rate of Rs 50 per liter would be Rs 57.2

Step-by-step explanation:

Given that,

Height of frustum, h= 7 cm

Lower radius, r= 4 cm

Upper radius, R= 10 cm

We know,

Formula of the volume of a frustum, v= 1/3*pi*h*(R^2 + r^2 + R*r)

Putting the given values, we get:

v= 1/3*22/7*7*(10^2 + 4^2 + 10*4)

v= 22/3(100 + 16 + 40)

v= 22/3*156

Solving we get,

v= 1144 cm^3

We know,

1000 cm^3 = 1 Litre

=>   1 cm^3 = 1/1000 Litre

So,

Volume of the frustum in litre= 1144*1/1000 = 1.144 Litre

Price of 1 litre oil = 50 Rs

So,

Price of 1.144 litre oil  = 50*1.144= 57.2 Rs