Question

The cost of fencing a circular field at the rate of Rs 12. per metre is Rs 2640 . find the radius of the field

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Answer 1

Radius = 35 m

Explanation:

Given:

Cost of fencing circular field is Rs 2640 at rate of Rs 12 per metre.

To Find:

What is the radius of the circular field ?

Solution:

Let the radius of circular field be r metre.

Here , if we'll divide the total cost by per metre cost of fencing then we'll get circumference of the circular field.

★ Circumference = Total cost/Cost per metre ★

➯ Circumference = 2640/12

➯ 220 m

As we know that , formula of circumference is

★ Circumference = 2πr ★

• ⟹ 220 = 2 × 22/7 × r
• ⟹ 220 = 44/7 × r
• ⟹ 220 × 7/44 = r
• ⟹ 20 × 7/4 = r
• ⟹ 5 × 7 = r
• ⟹ 35 = r

Hence, the radius of circular field is 35 metre.

Answer 2

Solution given:

total cost =Rs 2640

rate=Rs 12/metre

We have

circumference of circle =
`(total cost)/(rate) = (2640)/(12)`

2πr=220m

r=
`(220)/(2π)`=35.01

r=35m(approximately)

the radius of the field is 35m.