variance of ratio estimate

例句：

1. 1. The population of the city has seen a significant variance in recent years.
   这个城市的人口近年来发生了显著的变动。
2. 2.The weather forecast predicts a slight variance from yesterday's conditions.
   天气预报预测今天的天气与昨天的条件略有不同。
3. 3. The research team found that there was a noticeable variance in the results between different batches of samples.
   研究团队发现，不同批次的样本结果之间有明显的差异。