A plastic box 1.5 m long, 1.25 m wide and 65 cm deep is to be made. It is to be open at the top. Ignoring the thickness of the plastic sheet, determine:
(i) The area of the sheet required for making the box.
(ii) The cost of sheet for it, if a a sheet measuring `1m^2` costs Rs 20

Explanation

i) The dimension of the box is
Length l= 1.5 m

Breadth b= 1.25 m

Height h= 65 cm = 0.65 m
Area of the sheet required is
Area to be white-washed = Area of cuboid − Area of base

Area of sheet requred =`2lb+2bh+2lh−lb `

`[2×1.5×0.65+2×1.25×0.65+1.5×1.25] m^2`
The area of the sheet required for making the box is `5.45 m^2`
ii) The cost of sheet for it, if a sheet measuring 7m×3.5m costsर 510
i.e, area of sheet `24.5m^2 `cost Rs.510
So, 1 meter square cost
Now, The cost of 5.45 meter square cost