# There is 4 cm wide circular road around a circular field. Area of road

| There is 4 cm wide circular road around a circular field. Area of road is times of area of circular field. Find the radius of circular field is:

A. 15cm

B. 9cm

C. 25 cm

D. 20 cm

### Right Answer is: D

#### SOLUTION

Let area of circular field = 25 square units

So area of circular road =

Ratio of area of larger circle to smaller circle = (25+11) : 25 = 36 : 25

Ratio of radius of larger circle to smaller circle =

So difference in the radius of larger circle to smaller circle = width of road

⇒ 1 unit = 4 cm

⇒ 5 unit = 20 cm

So radius of circular field = 20 cm

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There is 4 cm wide circular road around a circular field. Area of road