"Question 1 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 1 m^2 costs Rs 20.
Class 9 - Math - Surface Areas and Volumes Page 213"
Answers
Surface area:
Surface area of a solid object is a measure of the total area that the surface of the object occupies and it is always measured in square unit.
Hence surface area is also known as total surface area TSA.
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Given:
Length of plastic box (l)= 1.5 m
Width of plastic box(b) = 1.25 m
Depth of plastic box(h) = 65cm = 65/100=0.65m
(i) The area of sheet required to make the box= surface
area of the box including the base &
excluding the top.
[Box is open at the top]
Surface area of the box = Lateral surface area +
Area of the base
= 2(l+b)×h + (l×b)
= 2[(1.5 + 1.25)×0.65] + (1.5 ×
1.25)
= 2(2.75)× 0.65 +1.875
=(3.575 + 1.875)
= 5.45 m²
The sheet required required to make the box is
5.45 m²
(ii) Cost of 1 m² of sheet = ₹
20
Cost of 5.45 m² of sheet = ₹ (20 × 5.45)
= ₹109
Cost of 5.45 m² of sheet = ₹ 109
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Hope this will help you..
1)We have , Length-1.5m
Breadth-1.25m
and Depth =Height.
1)Since the plastic box is open at the top.Therefore,
Plastic sheet required for making such a box
=[2(l+B)×h+lb]m^2
=[2×2.75+.65+1.875]m^2
=(3.575+1.875)m^2
=5.45m^2
2)Cost of 1 m square of sheet =Rs20
Total cost of 5.45 m square =Rs (5.45×20)
=₹109
Hope it is helpful⛎⛎⛎⛎