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 ✬

Step-by-step 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 ★

$\implies{\rm }$ 220 = 2 × 22/7 × r

$\implies{\rm }$ 220 = 44/7 × r

$\implies{\rm }$ 220 × 7/44 = r

$\implies{\rm }$ 20 × 7/4 = r

$\implies{\rm }$ 5 × 7 = r

$\implies{\rm }$ 35 = r

Hence, the radius of circular field is 35 metre.

Answer 2

Given :-

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

To Find :-

Radius

Solution :-

At first we need to find circumference

Circumference = Cost/Rate

Circumference = 2640/12

Circumference = 220 m

Now

Circumference = 2πr

220 = 2 × 22/7 × r

220 = 44/7 × r

220 × 7/44 = r

35 = r