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Question

_{The diameter of a roller is 84cm and it's length is 120cm.it takes 500 complete revolution to move once over to level a playground. Find the area of the playground in m²}

Answer 1

 

 1 revolution is the perimeter (or circumference) of the circle, 

   22/7 * diameter = 22/7 * 84 =  

                              22 * 12  <---- 7 cancels 84 by a factor of 12

                             264

 

So 1 revolution = 264 cm, which is the perimeter (or circumference) 

 

The length of the playground is 264 x 500 = 132000 cm

 

The width of the playground is the same as the length of the roller.

So 120 cm.

 

The area of the playground is 132000 cm x 120 cm = 15840000 square centimeters.

 

1 meter = 100 cm

1 square meter = 100 x 100 square cm

                        = 10000 square cm

 

So the area of the playground is 15840000 / 10000 = 1584 square meters