According to medical tests, when a person is still, a lot of heat is lost from the head. When the temperature is 15°C, the heat lost from the head accounts for 30% of the total body heat loss. It accounts for (3/5) when it is ℃, and (3/4) when it is minus 15 ℃. Therefore, there is a saying that "wearing a cotton hat in winter is like wearing a cotton jacket". At which temperature is the most heat lost from the head? How to compare faster?
据医学测试，人静止不动时，从头部散失的热量很多，在穿得暖和，但不戴帽子，气温为15℃时，从头部散失的热量占人体散失总量的30%，4℃时占(3/5)，零下15℃时占(3/4)，因此，有句俗话说"冬季戴棉帽，如同穿棉袄"．上面的哪个气温时从头部散失的热量最多？怎样比较更快一些？
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