# 6.2.4. Proportional Division

The number of pupils of a primary school in the first, second and the third grades is 285, if the ratio among the three grades is , calculate the number of pupils in each grade.

### Example

The number of pupils of a primary school in the first, second and the third grades is 285, if the ratio among the three grades is , calculate the number of pupils in each grade.

### Solution

We can use the concept of "the sum of parts" to solve this problem.

The sum of parts equal parts.

Since 19 parts pupils, then one part .

To find the share of pupils in the first grade, multiply the number of parts for that grade by the value of one part: pupils in the first grade.

To find the share of pupils in the second grade, multiply the number of parts for that grade by the value of one part: pupils in the second grade.

To find the share of pupils in the third grade, multiply the number of parts for that grade by the value of one part: pupils in the third grade.

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