1951 AHSME Problem 10

Of the following statements, the one that is incorrect is:

\textbf{(A)}\ \text{Doubling the base of a given rectangle doubles the area.}\qquad\textbf{(B)}\ \text{Doubling the altitude of a triangle doubles the area.} \textbf{(C)}\ \text{Doubling the radius of a given circle doubles the area.} \textbf{(D)}\ \text{Doubling the divisor of a fraction and dividing its numerator by 2 changes the quotient.} \textbf{(E)}\ \text{Doubling a given quantity may make it less than it originally was.}

Full credit goes to MAA for authoring these problems. These problems were taken on the AOPS website.