The unitary method is a method in which one finds the unit's value first and then the value of a required number of units. To give an instance, consider a motorcycle that runs 200 km on 20 litres of fuel. To determine how many it will run on 10 litres of fuel, one needs to try and identify the units (known) and values (unknown).
KM = Unknown (RHS)
No. of litres of fuel = Known (LHS)
Now, to solve this problem,
20 litres = 200 km
1 litre = 200 / 20 = 10 km
10 litres = 10 * 10 = 100 km
Hence this motorcycle will run 100 km on 10 litres of fuel.
The RD Sharma Class 7 Maths Chapter 10 unitary method also deals with the unitary method in ratio and proportion. In this case, if one needs to find the ratio of one quantity concerning the other, then it is recommended to use the unitary method. In addition to this, this chapter also covers some in-depth details on types of unitary methods.
Unitary approaches are classified into two types: direct variation and inverse variation. In a direct variation, increments or decrements in one quantity will cause the same effect on the other quantity. For example, an increase in the number of furniture units will cost more. On the contrary, in indirect or inverse variation, if we increase a quantity, then the other quantity's value decreases. For instance, if we increase the speed, we can cover more distance in a short period. Thus, increasing speed reduces the travelling time.
In addition to this, the applications of unitary methods are also discussed. Some of the major applications are as follows.