The ratio of a circle's radius to its diameter is always 1 to 2. In math class, Russell uses his compass to draw a circle with a radius of 6 centimeters.
What is the diameter of the circle Russell drew?
The question is telling the ratio of radius:diameter is 1:2. This means that to get the diameter from the radius, you must multiply by 2 (and divide the diameter by 2 to find the radius).
