Question

A plastic box 1.5 m long, 1.25 m wide and 65 cm deep is to be made. It is opened 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 7m×3.5m costsर 510.​

Answer 1

Answer:

Solution:

length - 1.5 m

Width - 1.25 m

depth - 65 cm

1. The area of the sheet required for making the box is equal to the surface area of the box including the top ......(!)

Surface area of the box= lateral area + Area of the base

= 2(l+b)×h + (l+b)

= (3.575 + 1.875)m²

= 5.45 m²

2 -

Cost of 1 m² of sheet = ₹ 20

cost of 5.45 m² = 5.45 × 20

= ₹109

Hope it will be helpful :)☺️

Answer 2

Length of box =1.5 m, Breadth =1.25 m, Height =0.65 m

⇒Area to be white-washed = Area of cuboid − Area of base.

(i) Area of sheet requred =2lb+2bh+2lh−lb

(i) Area of sheet requred =2lh+2bh+lb .....[Box is open]

=[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 5.45m²

area = Rs. 5.45×20

= Rs. 109