Sprinkler and Micro Irrigation

In a sprinkler irrigation test, the average catch depth across all collectors is $\bar{d} = 12\text{ mm}$, and the average catch depth in the lowest $25\%$ of collectors is $\bar{d}_{lq} = 9.6\text{ mm}$. The lower quarter distribution uniformity $DU = (9.6 / 12.0) \times 100$ in percent is: