variance of a random variable

例句：

1. 1.The population of the city has a significant variance in income levels.
   这个城市的居民收入水平存在显著的变异。
2. 2. Variations in temperature can affect the growth of crops.
   温度的变化会影响农作物的生长。
3. 3. The variance between the two groups is statistically significant.
   两组之间的差异在统计学上是显著的。