Question

The areas of two concentric circles are 962.5 cm2 and 1386 cm2. Find the width of the ring formed by them

Answer 1

Area of bigger circle =πR²
1386 = 22/7 × R²
R² = 1386×7/22
R² = 441
R = 21cm

Area of smaller circle = πr²
962.5 = 22/7 × r²
r² = 962.5 ×7/22
r² = 306.25
r = 17.5cm

Width of ring = 21-17.5
= 3.5cm

Answer 2

Area of bigger circle =πR²

1386 = 22/7 × R²

R² = 1386×7/22

R² = 441

R = 21cm

Area of smaller circle = πr²

962.5 = 22/7 × r²

r² = 962.5 ×7/22

r² = 306.25

r = 17.5cm

Width of ring = 21-17.5

= 3.5cm