The complete grouped relative frequency distribution is as follows:
- Quiz score \(66\) to \(71\): \(0.47\)
- Quiz score \(72\) to \(77\): \(0.13\)
- Quiz score \(78\) to \(83\): \(0.27\)
- Quiz score \(84\) to \(89\): \(0.13\)
Thus, the final answer is:
\[
\boxed{
\begin{array}{|cc|}
\hline
\text{Quiz score} & \text{Relative frequency} \\
\hline
66 \text{ to } 71 & 0.47 \\
72 \text{ to } 77 & 0.13 \\
78 \text{ to } 83 & 0.27 \\
84 \text{ to } 89 & 0.13 \\
\hline
\end{array}
}
\]