Question

The area of a circular playground is 22176 m2. Find the cost of fencing this ground at the rate of Rs 50 per metre
NCERT Class X
Mathematics - Exemplar Problems
Chapter _AREA RELATED TO CIRCLES

Answer 1

area of circular ground= 3.14 x r x r
22176m2=3.14 x r x r
rxr=7062.42
r=84.04m
circumference= 2 x 3.14 x 84.04
                       =527.77m
cost of fencing=50 x 527.77
                       =Rs 26388.50 

Answer 2

Area = 22176 m²
Area of a circle = πr²

22176 = πr²
r² = 22176×7/22
r² = 7056
r = √7056
r = 84 m

Now, circumference of the circle = 2πr = 2×22/7 × 84 = 528 m

Cost of fencing per m= Rs.50
Cost of fencing 528 m = Rs.50 × 528
= Rs.26400