Question

5. The diameter and length of a roller is 120 cm
and 84 cm respectively. To level the ground,
200 rotations of the roller are required. Find
the expenditure to level the ground at the rate
of 10 per sq. m.​

Answer 1

Given :-

▪ The diameter and length of a roller is 120 cm and 84 cm respectively. The roller requires 200 rotations to level the ground.

▪ Rate of leveling the ground is 10 per sq. m

To Find :-

▪ Cost of leveling the ground.

Solution :-

First, We would have to find the area of the ground. Since the measurements of the roller have been given, we can find the curved surface area of the roller.

We have,

• Radius, r = 120 / 2 = 60 cm
• Length, l = 84 cm

Since, The roller is in cylindrical shape, so

⇒ Curved Surface area = 2πrh

⇒ CSA = 2×22/7×60×84

⇒ CSA = 44 × 12 × 60

⇒ CSA = 31,680 cm²

Since, The roller takes 200 rotations, which means it covers its curved surface area 200 times which is the area of the ground, so

⇒ Area of ground = 200 × 31680

⇒ Area of ground = 6336000 cm²

The rate is given in sq. m, So let us convert the area of the ground into m² by dividing the value by 10000,

⇒ 6336000 / 10000

⇒ 633.6 m²

Let's find the cost now,

⇒ Cost = Rate × Area

⇒ Cost = 10 × 633.6

⇒ Cost = ₹ 6336

Hence, The cost of leveling the ground is ₹ 6336

Answer 2

Answer:

I hope it helps you.....