AMC 12 2011b Problem 9

Two real numbers are selected independently and at random from the interval $[-20,10]$. What is the probability that the product of those numbers is greater than zero?

\textbf{(A)}\ \frac{1}{9} \textbf{(B)}\ \frac{1}{3} \textbf{(C)}\ \frac{4}{9} \textbf{(D)}\ \frac{5}{9} \textbf{(E)}\ \frac{2}{3}