The circumferences of two circles are in the ratio of 2:5. The radius of the smaller circle is 16 in. What is the radius of the larger circle?

A circle’s circumference is proportional to its radius because C = 2πr. So the radii have the same ratio, 2:5. If the smaller radius is 16 in., the larger radius is 16 × 5 ÷ 2 = 40 in., which is choice B.

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