1. After getting rid of the Colorado potato beetle, the farmer started to harvest as much potato from 24 hectares as he used to from 27 hectares. By what percentage did the potato yield increase?
Answer: $12.5 \%$.

Solution. From 24 hectares, the farmer began to collect $27 / 24=1.125$ times more potatoes than before. This means that the potato yield increased by $12.5 \%$.