2. The first and last items of the ratio can be any number ().

3. Four numbers must form a proportion ()

4. In proportion, the product of two introverts is equal to the product of two external items ()

5. The first item and the last item of the ratio are multiplied or divided by a number that is not equal to 0 at the same time, and the size of the ratio remains unchanged ().

6. The number of A is 1. 5 times that of B, and the ratio of B to A is 5:6 ().

7. The ratio of side length to perimeter of a square is 4: 1 ()

8. The perimeter ratio of two squares is 4:5, and the area ratio is 16:25 ().

9. In proportion, the two external terms are 7 and 5 respectively, and the product of the two internal terms is 35 ().

10.1/2:1/3 The simplest integer ratio is 2:3 ().

1 1. The ratio of boys to girls is 4:5, and there are fewer boys than girls 1/4 ().

12. The ratio of the area of an equilateral parallelogram to that of a triangle is 2: 1 ().

13. Two kinds of exercise books, one for 3 yuan and the other for 4 yuan. The simplest integer ratio of the unit price of these two kinds of exercise books is 16: 15 ().

14. Put 1g salt into 10g water, and the ratio of salt to water is 1:99 ().

15. If 7a = 8b (A and B are not equal to 0), then 7/8=b/a ().

1× 2× 3 4√ 5√ 6√ 7× 8√ 9√ 10× 1 1× 12√ 13× 14× 15√