Question

The diameter and height of a cylindrical tank are 7$m$ and $9m$ respectively. If the inner side of the tank has to be painted all over, what will it cost at Rs $35$ per square metre?

• A. Rs.$6420.8$
• B. Rs.$9420.8$
• C. Rs.$6620.8$
• D. Rs.$9620.8$

Answer 1

The correct option is D Rs.$9620.8$

With a diameter of $7m$, the circumference
$=\pi \times 7=21.99$m
The height =$9$m
Surface area $=21.99\times 9+2\times \pi \times {3.5}^2$

Surface area $=197.91+76.97$
Surface area $=274.88m^2$
Cost = $274.88m^2\times Rs35$
Cost $=Rs9620.8$