Unitary Method

Unitary Method

Finding the value of one unit and then using it to find the value of the required number of units is known as unitary method.

Steps involved in Unitary Method

● Express the given problem in Mathematical statement.

● Find the value of one unit of the given item using division.

● Find the value of the required number of the same items using multiplication.

Example 3.8

Pari wants to buy 5 tennis balls from a sports shop. If a dozen balls cost ₹180, how much should Pari pay to buy 5 balls?

By unitary method, we can solve this as follows :

Cost of a dozen balls = ₹ 180

⇒ Cost of 12 balls = ₹ 180

Cost of 1 ball = 180/12  = ₹ 15

Cost of 5 balls = 5 × 15 = ₹ 75

Hence, Pari has to pay ₹ 75 for 5 balls.

Example 3.9

A heater uses 3 units of electricity in 40 minutes. How many units does it consume in 2 hours?

Solution

In 40 minutes, electricity used = 3 units.

In 1 minute, electricity used = 3/40 units.

In 120 minutes (2 hours), electricity used = 3/40 × 120 = 9 units

 Thus, the heater consumed 9 units of electricity in 2 hours.