如图为“我国南北方河川径流量和耕地的百分比图”，据图完成下面小题：
在500个数据中，用适当的方法抽取50个为样本进行统计，频率分布表中54.5～57.5这一组的频率是0.15，那么估计总体数据在54.5～57.5之间的约有（ ）
阅读短文，判断正误。
It was Saturday yesterday. It was sunny. Li Lei helped his mother do the housework in the morning. He went to the park with his friends in the afternoon. They played football in the park. His sister Li Mei played computer games at home. Their father, Mr. Li, watched TV at home.
①是维护国家安全、荣誉和利益的表现 ②是坚持国家利益高于一切的表现
③是维护国家主权和领土完整的表现 ④是我国国防力量超过美国的表现
