The cross section of a tunnel perpendicular to its length is a trapezium ABCD as shown
the figure. AM = BN; AB = 4.4 m; CD = 3 m.
The height of the tunnel is 2.4 m. The tunnel is
50 m long.
D 3m C
1
124 m
1
А
M N
4.4 m
B
Calculate :
(i) the cost of painting the internal surface of
the tunnel (excluding the floor) at the rate
of 5 per m.
(ii) the cost of paving the floor at the rate of
18 per m
(ICSE)
rith its parallel sides in the ratio
Answers
Answer:
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Asked on December 30, 2019 by
Yamini Dabral
The cross-section of a perpendicular to its length is a trapezium ABCD as shown in the figure also given that :
AM = BN; AB = 7 m; CD = 5 m. The height of the tunnel is 2.4 m. The tunnel is 40 m long. Calculate the cost of painting the internal surface of the tunnel (excluding the floor) at the rate of Rs. 5 per m
2
(sq. metre.).
196128
MEDIUM
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ANSWER
AM=BN=
2
7−5
=
2
2
=1m
In △ADM
AD
2
=AL
2
+DL
2
=>AD
2
=1
2
+2.4
2
=>AD
2
=1+5.76
=>AD
2
=
6.76
=>AD=2.6m
Perimeter of the cross section of the tunnel =(5+2.6+2.6+7)m
=17.2m
Length =40m
∴ internal area of the tunnel(except floor)
=17.2×40−40×7
=688−280
=408m
2
Rate of painting=5m
2
=408×5m
2
=2040Rs
Answer:
just do what I say......okay