[Reward - Medal and Fan]
A cylindrical oil tank has diameter 7m and height 9m. If the Inner side of the tank has to be painted all over, what will it cost at $35 per square metre?

Question

[Reward - Medal and Fan]
A cylindrical oil tank has diameter 7m and height 9m. If the Inner side of the tank has to be painted all over, what will it cost at $35 per square metre?

myininaya · Answer

I guess inner side means 
inside and just on the walls of the tank not including the inner roof or base of the tank

anonymous · Answer

@myininaya yeah

myininaya · Answer

|dw:1416062174101:dw|
first of all this is a cylinder 
we don't want to consider it as a solid cylinder
we want to consider it as a hollow cylinder ...
do you know the circumference of a circle ?