Class 7 Chapter 8: Ratio and Proportion

Class 7 Chapter 8: Ratio and Proportion

Important Concepts and Formulas on Ratio and Proportion

1.      Ratio is a way of comparing two quantities of the same kind.

2.      While calculating the ratio of two given quantities, both the quantities must be in the same unit.

3.      The ratio a : b is not same as the ratio b : a.

4.      The first term of a ratio is called the antecedent and the second term is called the consequent.

5.      Normally a ratio is expressed in its simplest form.

6.      The ratios a : b and c : d are equivalent ratios if a/b and c/d are equivalent fractions.

7.      We can compare two ratios by converting the ratios in their fractional forms.

8.      If two ratios are equivalent, then the four quantities involved in these two ratios are said to be in proportion. Four quantities a, b, c, d are said to be in proportion if a : b = c : d.

9.      First and fourth terms (i.e., end terms such as a and d) of a proportion are called extremes and the middle terms (i.e., the second and third terms such as b and c) are called means.

10. If four terms are in proportion, then product of extremes = product of means.

11. The rule ad = bc is used to check whether a, b, c, d are in proportion or not.

12. A method in which we first find the value of one unit and then find the value of the required number of units is called unitary method.