Question

A plastic box 1.5 m long. 1.25 m wide and 65 cm
deep is to be made.it is opened at top.ignoring the thickness of the plastic sheet, determine:
The area of the sheet required for making the box.
The cost of sheet for it, if a sheet measuring 1m^2costs Rs 20.
m and 3 m respectively​

Answer 1

Answer:

length=1.5m

Breadth=1.25m

Height=65cm =0.65m

TSA of the cuboid excluding the top=2(bh+lh)+lb

=2(1.25*0.65+1.5*0.65)+1.5*1.25

=2(0.8125+0.975)+1.975

=2*1.7875+1.975

=5.45m square

Cost of sheet for 1m square=Rs20

Cost of sheet for 5.45m square=5.45*20

=Rs109

Answer 2

Answer:

Given:

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