After learning the positive and negative proportions in the next semester of the sixth grade, some questions in the junior high school mathematics exam have been assigned to be answered by proportions. That was not the case. Here comes the problem. If some students are familiar with the original arithmetic methods, they can propose a proportional solution, sometimes they don't know how to start. Let's share two examples, hoping to play a role in attracting jade.

Example 1: as shown below.

Analysis: There are two related quantities "shadow length and object height" in this question. You should know that these two related quantities are directly proportional, that is, the shadow length and the height of the object change in the same direction, and the direct ratio is a quotient or a ratio. When the column ratio is set, it is written in the form of two groups of ratios. White pagoda height: white pagoda shadow length = bamboo pole height: bamboo pole shadow length. It is also possible to exchange the positions of the front and rear terms of the two groups of ratios, in short, at the same time.

8 cm =0.08 m

Solution: the height of the white tower is x meters.

3.2:X=0.08: 1.6

X=64

The height of the White Pagoda is 64 meters.

Example 2: As shown below.

Analysis: this question has two related quantities: the number of people in each row and the number of stations in each row. The more people in each row, the fewer stations in each row. These two related quantities change in opposite directions. The product of these two related quantities represents the total number of people, and the total number of people is certain. The number of people in each row is inversely proportional to the number of stations in each row, and the inverse ratio is listed as the product of two groups. The number of people in each row is 65438.

Solution: suppose we can stand in row X.

50X=30×25

X= 15

Answer: Just stand in row 15.

Example 3: As shown below.

Analysis: There are two quantities "side length and number of blocks" in this question, but they are not directly related, because the area of a square brick is equal to the side length multiplied by the side length, so "the area of a square brick and the number of blocks of a square brick" are two related quantities. The area of square brick is large, and the number of blocks required is small, but the number of blocks required is large. The two related quantities change in opposite directions, and the product of square brick area and block number must be certain.

Solution: Suppose X blocks are needed.

(60×60)X=40×40×270, without brackets, just write brackets, and 60×60 in brackets represents the square brick area, which is a whole;

X= 120

A: Yes 120 yuan.