Question

A circle has a diameter of 6 inches. Hoshi found the area by wrongly using the diameter instead of radius in the area formula. How many times greater is the area of the circle Hoshi found compared to the actual area? Explain how you know.

Answer 1

Since area is found by radius, we must decide what should have been used. Take half of 6 and you have 3.

Now squaring 3, using the formula gives us 9. Hoshi squared 6 giving him 36. This is 4 times greater. That's because his value was 2 times greater and when we squared it that made it 2 more times greater, or 4 times greater.

Pi cancels itself and does not affect the outcome.