The relative frequency is the ratio of the frequency to the total number of data, expressed in percentage.

Here, the total number of data is \(5+11+16+5+1=38\). Hence, the relative frequencies are:

\(\begin{array}{|c|c|}\hline \text{Grade} & \text{Frequency} & \text{Relative frequency} \\ \hline A & 5 & \frac{{5}}{{38}}\sim{0.1316}\to{13.16}\% \\ \hline B & 11 & \frac{{11}}{{38}}\sim{0.2895}\to{28.95}\% \\ \hline C & 16 & \frac{{16}}{{38}}\sim{0.4211}\to{42.11}\% \\ \hline D & 5 & \frac{{5}}{{38}}\sim{0.1316}\to{13.16}\% \\ \hline F & 1 & \frac{{1}}{{38}}\sim{0.0263}\to{2.63}\% \\ \hline \end{array}\\\)

Note: If 42.11% does not work, try 42.10%.