In a circle, if radius is doubled, what happens to the area?

If the radius of the circle is increased by 100%, then the area is increased by

The ratio of the radius of two circles is 5:4. What is the ratio of their areas?

The area of a circle is 40π² . The area of a square with sides equal to radius of the circle is

If radius of a circle is increased by 10%, percentage increase in area is

If the difference between the circumference and radius of a circle is 37 cm, then the area of the circle is