To compare \(5 \times 10^{-11}\) and \(3 \times 10^{-11}\), we can look directly at the coefficients, since they both have the same exponent.
Since \(5 > 3\), we can conclude that:
\[5 \times 10^{-11} > 3 \times 10^{-11}\]
Therefore, the correct symbol to fill in the blank is:
\[
\]