Question

the diameter of a 120 cm long roller is 84 cm It takes 1000 complete revolutions in moving once over to level a playground what is the area of the playground​

Answer 1

★Solution :

➪ Length of roller = 120 cm.

➪ Diameter of roller = 84 cm.

➪ Radius of roller = $\dfrac{(Diameter)}{2}$

= $\dfrac{84}{2}$

= 42 cm

As we know, a roller is in the shape of cylinder.

➪Perimeter of roller = Area covered by roller in 1 one revolution = 2 × π × (radius ) × length

➪Perimeter = 2×( $\dfrac{22}{7}$ ) × 42 × 120

➪Perimeter = 44 × 6 × 120

➪Perimeter = 31,680 cm²

Therefore,

➪Area covered by wheel in 1000 revolutions

= (31,680×1000) cm²

= $\dfrac{31,680,000}{10000}$

Answer = 3,168m²

Hence, Area of Playground is 3,168m²

Answer 2

Answer:

●Radius of the roller (r)=84/2cm=42cm

●length of the roller (h)=120cm

●∴ Area of the playground levelled in taking 1 complete revolution 2πrh

●=2×227×42×120=31680cm2

●∴ Area of the playground

●=31680×1000

●=31680000

●= 31680000/100 × 100m²

●= 3168m2