ratio estimates in stratified random sampling

例句：

1. 1. The city is divided into several stratified neighborhoods.
   这个城市被分成了几个分层的社区。
2. 2. The data was organized in a stratified manner for easier analysis.
   数据以分层方式组织，以便更容易分析。
3. 3. The museum exhibits stratified fossils from different eras.
   博物馆展示了不同时代的分层化石。