Fourth proportional: the same quantity
Solve problems with a quantity that stays the same (the mass of one box, a price, a total mass): find it first, then answer the question.
- Ukraine: grade 3
- Russia: grade 3
Guide
Ukrainian Grade 3 (part 2) teaches problems of the fourth proportional. They have two situations and one quantity that is the same in both: the mass of one box, the price of one pencil, or the total mass.
The short record is a table with rows I and II. The same quantity is written once between the rows: "?, the same". The plan: 1. Find the value of the same quantity. 2. Answer the question of the problem.
If the unknown changes, we get inverse problems, and the key is still the same: the same quantity first.