## 31. Math Puzzle 12/67

From a statistic, it is evident that only about $15 \%$ of the agriculturally used land area of our Earth is regularly irrigated, and this area produces $25 \%$ of the world's harvest.

How many times greater is the average yield per hectare of the irrigated area compared to that of the non-irrigated area?
The base value $G$ is, on the one hand, the agriculturally used area of our Earth, and on the other hand, the total world harvest $E$. The question is about the ratio of the average yield per hectare of the irrigated area, which we call $B$, to the non-irrigated area, which we call $U$. Then it follows that

$$
0.25 \cdot E = 0.15 \cdot G \cdot B ; 0.75 \cdot E = 0.85 \cdot G \cdot U \rightarrow \frac{B}{U} = \frac{17}{9} \approx 1.9
$$

The yield per hectare of the irrigated area is almost twice as large as that of the non-irrigated area.