CBSE Class 6 Maths Chapter 12 Notes Ratio and Proportion

Ratio and Proportion Class 6 Notes Conceptual Facts

1. The comparison of two quantities by division is called ratio.
For example,\(\frac{2}{3}, \frac{1}{2}, \frac{1}{3}, \frac{1}{4}\)etc.

2. We represent the ratio by a symbol V
For example: \(\frac{2}{3}\) = 2:3 or \(\frac{3}{2}\) = 3:2

3. Two quantities can only be compared when they are in the same unit.
For example, 4 cm : 5 cm or \(\frac{3}{2}\) m \(\frac{4}{5}\)m

4. We can get equivalent ratios by multiplying or dividing the numerator and the denominator by the same number. For example, \(\frac{2}{3}=\frac{2 \times 2}{3 \times 2}=\frac{4}{6}=\frac{4 \times 3}{6 \times 3}=\frac{12}{18} \cdot \mathrm{So}, \frac{2}{3}, \frac{4}{6} \text { and } \frac{12}{18}\) are all equivalent ratios.

5. If two ratios are equal, we say that they are in proportions and use the symbol :: or *=’.
For example, 2 : 3 :: 4 : 6 or 2 : 3 = 4 : 6

6. If two ratios are not equal then we say that they are not in proportion.
For example, \(\frac{2}{3} \text { and } \frac{4}{5}\) are not equal ratios. So they are not in proportions.

7. In proportion four quantities are involved. The first and fourth terms are known as extreme and second and third terms are known as middle terms.
For example, 2 : 3 :: 8 : 12 where 2 and 12 are extreme and 3 and 8 are middle terms.

8. Product of extreme terms = product of middle terms.

9. We can use a method in which first we find the value of one unit and then the value of the required number of units. This method is called the unitary method.