What is the ratio of a circle's Radius to its circumference?

The radius of a circle is 4.7 cm. Find its circumference

The radius of a circle is 10.5 cm. Find its circumference.

What is the radius of a circle, whose sum of circumference and the radius is 51 cm?

Find the radius of a circle if its circumference is 88 cm

If the area of circle is 616 cm², then what is its circumference?

The radius of a circle is increasing at the rate of 0.7cm/s .What is the rate of increase of its circumference?