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the diameter of the roller 120 cm long is 84 cm. if it takes 500 complete revolutions to level a playground, determine the cost of levelling at the rate of 30 paise per sq. m.

plzz its urgent plzz give me fast ans...today is my test

Diameter = 84cm

Radius = 42cm

Height = 120cm

1 revolution = LSA of roller

= 2 x (22/7) x 42  6 x 120

= 31680 cm2

So, 500 revolutions = 31680 x 500

= 15840000cm2

1 cm2 = .0001m2

So,  15840000cm2 = 1584 m2  

Cost = 1584 x .30

= Rs 475.20

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The cost of fencing a field at the rate of Rs. 24 per meter is Rs. 5280. The field is to be ploughed at the rate of 0.50 ps per square meter. Find the cost of ploughering the field.
 
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@Shanthan this the answer:-

amount of fencing = Rs 5280
cost of fencing = Rs 24 per metre

lenghth of field = 5280
                               24
                          = 220 m

Circumference of circle = ​2πr
                           220  = 2 x 22 x r [ HERE MANDATORY TO TAKE π = 22 ]
                                             7                                                                   7

                                 r = 220 x 7
                                       2 x 22
                                r = 35 m

Area of circle = π​r2
                      = 22 x 35 x35
                          7
                      = 3850 m2

Rate of ploughing the field = 0.50 paisa per square metre
Cost of fencing the field = 3850 m2 x 0.50 paisa per m2
                                       = Rs 1925

Hence, the cost of fencing the field is Rs 1925
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