solve this sum?

Question

http://img149.imageshack.us/img149/4328/untitledfl1.png

Answer 1

Area of outer ring = Area of big circle minus area of little circle.
Area of outer ring = π(4r)² - π(1)r²
Area of outer ring = 16π r² - π r²
Area of outer ring = 16² units.

If I understand this question correctly:
You want the perimeter of the inner circle and outer circle added together.
Total length = 2π(4)r + 2π(1)r
Total length = 8π r + 2π r
Total length = 10π r

Perimeter of small circle = 2π(1)r
Perimeter of small circle = 2π r

Answer 2

Area of Outer Ring = area of the whole circle -area of small circle
Area of Outer Ring = pi (5r)^2 - pi(r)^2
Area of Outer Ring = 25r^2 * pi - r^2 * pi
Area of Outer Ring = 24r^2*pi

Area of the small circle = pi*r^2

Perimeter of the inner circle = 2r * pi