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 sheet measuring 1m2 costs Rs. 20.

 Solution:

Given: length (l) of box = 1.5m

Breadth (b) of box = 1.25 m

Depth (h) of box = 0.65m

(i) Box is to be open at top

Area of sheet required.

= 2lh+2bh+lb

= [2×1.5×0.65+2×1.25×0.65+1.5×1.25]m2

= (1.95+1.625+1.875) m2 = 5.45 m2

(ii) Cost of sheet per m2 area = Rs.20.

Cost of sheet of 5.45 m2 area = Rs (5.45×20)

= Rs.109.