NCERT Solution For Class 6, Maths, Chapter 12, Ratio and Proportion

key points:

Ratio: Aratio is a comparison of two quantities. For comparison by ratio, the two quantities must be in the same unit. If they are not, they should be expressed in the same unit before the ratio is taken.

The ratio of ‘x’ and ‘y’ can be expressed as $\frac{x}{y}$. For example, Ruchi’s weight is 25 kg and her father’s weight is 75 kg. We say that Ruchi’s father’s weight and Ruchi’s weight are in the ratio 3 : 1.

Proportion: A proportion is an equality of two ratios.  In many situations, a more meaningful comparison between quantities is made by using division, i.e. by seeing how many times one quantity is to the other quantity. This method is known as comparison by ratio.

For example, John’s age is 25 years and his father’s age is 75 years. We say that John’s father’s age and John’s age are in the ratio 3 : 1.

A ratio can be expressed in its lowest form. For example, ratio 50: 15 is treated as $\frac{50}{15}$ in its lowest form. Hence, the lowest form of the ratio 50: 15 is 10: 3.