1. 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:
( The area of the sheet required for making the box.
(1) The cost of sheet for it, if a sheet measuring 1m² costs * 20.
The length hreadth and height
Answers
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] m
2
=(1.95+1.625+1.875)m
2
=5.45 m
2
ii) Cost of sheet per m
2
area = Rs. 20
Cost of sheet of 5.45m
2
area = Rs. 5.45×20
= Rs. 109
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 1m2 costs ₹20.
Answer :-
(i) Here, length (l) = 1.5 m, bread th(b) = 1 .25 m
and height (h) = 65 cm = 65/100 m = 0.65 m
∵ It is open from the top.
∴ Its surface area
= [Lateral surface area] + [Base area]
= [2(1 + b)h] + [lb]
= [2(1.50 + 1.25)0.65] m2 + [1.50 x 1.25] m2
= [2 x 2.75 x 0.65] m2 + [1.875] m2
= 3.575 m2+ 1.875 m2 = 5.45 m2
∴ Area of the sheet required for making the box = 5.45 m2
(ii) Cost of 1 m2 sheet = Rs. 20
Cost of 5.45 m2 sheet = Rs. (20 x 5.45)
= Rs. 109
Hence, cost of the required sheet = Rs. 109
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