Proportional division and the same quantity
Solve problems with the short record price, count, cost: proportional division and finding the same quantity from two differences or two sums.
- Ukraine: grade 4
- Russia: grade 4
Guide
In Ukrainian Grade 4 pupils solve proportional-division problems. There are usually three quantities: price (or productivity), count (or time) and cost (or total output). One of them is the same in both cases and is marked "однак." in the short record.
Example: 135 UAH was collected for 7 figurines and 8 napkins at the same price. First count all items: 7 + 8 = 15. Then the price of one: 135 : 15 = 9 (UAH). Finally the cost of each kind: 9 · 7 and 9 · 8.
In "two differences" problems the unknown same quantity is found from the difference of two other quantities. For example 4 more bars cost 100 UAH more, so one bar costs 100 : 4 = 25 (UAH). In "two sums" problems first remove the common part by subtracting one sum from the other.