Explanation:
The area of a circle is given by :
A = πr²
r is radius of the circle
(4) Diameter = 22 cm
Since, radius = diameter/2
r = 11 cm
Now, area of the circle,

(5) Diameter = 30 cm
Since, radius = diameter/2
r = 15 cm
Now, area of the circle,

(6) Diameter = 4cm
Since, radius = diameter/2
r = 2 cm
Now, area of the circle,

Hence, this is the required solution.