Adrian measures the circumference of a circular picture frame, with a radius of 3 inches. Which of the following is the best estimate for the circumference of the frame?
The circumference of a circle can be found by using the formula, $3969_w59_h13.png$. Since the radius is equal to 3 inches, the diameter is equal to 6 inches. Substituting a value of 6 inches for d and estimating pi to be 3, gives an approximate circumference of 18 inches.