Q : 1 A wooden bookshelf has external dimensions as follows: Height , Depth , Breadth (see Fig. ). The thickness of the plank is everywhere. The external faces are to be polished and the inner faces are to be painted. If the rate of polishing is paise per and the rate of painting is paise per , find the total expenses required for polishing and painting the surface of the bookshelf.
External dimension od the book shelf =
(Note: There is no front face)
The external surface area of the shelf =
We know, each stripe on the front surface is also to be polished. which is 5 cm stretch.
Area of front face =
Area to be polished =
Cost of polishing area =
Cost of polishing area =
Now,
Dimension of inner part =
Area to be painted in 3 rows =
Cost of painting area =
Cost of painting area =
Total expense required for polishing and painting =