Q. 74.2( 38 Votes )
The diameter of a roller is 84 cm and its length is 120 cm. It takes 500 complete revolutions to roll once over the play ground to level. Find the area of the play ground in m2.
Answer :
Given, diameter = 84cm = 0.84m i.e r = 0.42m
Length h = 120cm = 1.20m
Number of revolutions n = 500
Area of the playground = n × curved surface area of the roller
= 500 × 2πrh
= 500 × 2 × 3.14 × 0.42 × 1.2
= 1582.56m2
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PREVIOUSA cylindrical piller has a diameter of 56 cm and is of 35 m high. There are 16 pillars around the building. Find the cost of painting the curved surface area of all the pillars at the rate of 5.50 per 1 m2.NEXTThe inner diameter of a circular well is 3.5 m. It is 10 m deep. Find(i) its inner curved surface area(ii) The cost of plastering this curved surface at the rate of Rs. 40 per m2.
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