Math
posted by Tim .
If the diameter of a circle is 5 in., what is the radius?
What is the relationship of the diameter of a circle to radius?

The diameter is the distance across the circle and the radius is the distance from the center of the circle to the edge of the circle.
I will be happy to check your answer. 
2.5?

Right. The radius is 2.5
So you can see that the diameter is double the radius.
or you can say the radius is 1/2 the diameter.