Question

10.
A bOX made of sheet metal costs 2820 at the rate of 30 per square metre. If the box 15
5 m long, 4 m wide, find its height.

11. Four cubes each of side 3 cm are joined end to end. Find the surface area of the resume

12. Aditya has built a cubical water tank with lid for his house, with each outer edge equal to
1.5 m. He gets the outer surface of tank including the base, covered with square tiles of
side 25 cm. Find how much he would spend for tiles if the cost of tiles is 480 per dozen
13. An open water tank 12 m long 9 m wide and 4 m deep is to be made. Determine the cost
of iron sheet required at the rate of 25 per m, if the sheet is 1.5 m wide.
14. Find the curved surface area and the total surface area of a cylinder whose radius is 3.5 m
and height is 6 m.
15. The area of the curved surface of a cylinder is 4400 cm² and the circumference of its base
is 110 cm. Find the height of the cylinder.
16. Twenty-one cylindrical pillars of a building have to be cleaned. If the diameter of each
pillar is 50 cm and the height is 4 m, find the cost of cleaning them at the rate of
1.50 per m²
17. The diameter of a circular well is 4.5 m and its depth is 7 m. Find the cost of cementing
the inner curved surface of the well at the rate of 3.50 per m².
18. A circular tunnel of diameter 2 m and length 1.4 km is dug out. Find the cost of plastering
it at * 150 per 100 m².​

Answer 1

Step-by-step explanation:

Total cost=2820

Rate of cost=30/m^2

length of box=5m

breadth of box=4m

Area of metal sheet=2(lb+bh+lh)

=2(5×4+4h+5h)

=2(20+9h)

=40+18h

cost of sheet=area of sheet ×cost for 1m^2 of sheet

2820=(40+18h)×30

94=40+18h

18h=54

h=3

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