数学思想是解题的灵魂,下面举例说明转化思想的应用.例1如图1,一个啤酒瓶的高度为30cm,瓶中装有高度12cm的水.将瓶盖盖好后倒置,这时瓶中水面高度20cm,则瓶中水的体积和瓶子的容积之比为().(圆柱体的体积等于底面积乘以高,瓶底厚度不计) Mathematical thinking is the soul of problem solving. Here is an example of the application of the idea of ​​transformation. Example 1 As shown in Figure 1, a beer bottle has a height of 30cm and the bottle is filled with water of height 12cm. When the bottle cap is covered, it is inverted and the bottle is inverted. When the height of the water surface is 20cm, the ratio of the volume of water in the bottle and the volume of the bottle is (). (The volume of the cylinder is equal to the bottom area multiplied by the height, the thickness of the bottom of the bottle is not counted)