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EXERCISE 13.1
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:
0 The area of the sheet required for making the box.
(i) The cost of sheet for it, if a sheet measuring Im costs Rs 20.
The length, breadth and height of a room are 5 m, 4 m and 3 m respectively. Find the
cost of white washing the walls of the room and the ceiling at the rate of
Rs 7.50 per m.
3. The floor of a rectangular hall has a perimeter 250 m. If the cost of painting the four
walls at the rate of Rs 10 per m is Rs 15000, find the height of the hall.
[Hint: Area of the four walls Lateral surface area.
4. The paint in a certain container is sufficient to paint an area equal to 9.375 m. How
many bricks of dimensions 22.5 cm * 10 cm x 7.5 cm can be painted out of this
container?
chedae 10 cm and another cuboidal box is 12.5 cm long. 10 cm
Answers
Answer:
Ur answer is here-
Explanation:
1-
To find :
(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.
Solution :
i) The dimension of the box is
Length l= 1.5 m
Breadth b= 1.25 m
Height h= 65 cm = 0.65 m
Area of the sheet required is
The area of the sheet required for making the box is 5.45 meter square.
ii) The cost of sheet for it, if a sheet measuring 7m×3.5m costsर 510.
i.e, area of sheet 24.5 meter square cost Rs.510
So, 1 meter square cost
Now, The cost of 5.45 meter square cost
Therefore, The cost of sheet is Rs. 113.447.
3-
Perimeter of rectangular hall = 2(l + b) = 250 m
Total cost of painting = Rs.15000
Rate per m2 = Rs.10
Area of four walls = 2(l + b) h m2 = (250×h) m2
A/q,
(250×h)×10 = Rs.15000
⇒ 2500×h = Rs.15000
⇒ h = 15000/2500 m
⇒ h = 6 m
Thus the height of the hall is 6 m.
4-
Length = 22.5
Breadth = 10 cm
Height = 7.5 cm
so , the area = 2(lb + bh + hl )
= 2 (22.5*10 + 10*7.5+22.5*7.5 )
= 2 ( 225 + 75 + 168.75 )
= 2 * 468.75
= 937.5 cm units
Therefore , Bricks = Area painted by a container / Area of a brick
= 9.375 * 10000 / 937.5
= 100 bricks
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