Unitary Method: Steps, Types of Unitary Method, Solved Examples

Jasmine Grover logo

Jasmine Grover

Content Strategy Manager

Unitary method is process of finding value of single unit by using value of multiple units and then finding value of multiple units using value of single units. This method is mostly used in ratio and proportion concept. Unitary Method has two variations, direct variation and indirect variation. Direct variation is inverse to indirect variation. Unitary method is used to determine price of a good, profit or loss in business, calculating percentage, etc.

Key Terms: Unitary Method, Ratio, Proportion, Single Units, Multiple Units, Direct Variation, Indirect Variation


Introduction to Unitary Method

[Click Here for Sample Questions]

Procedure of finding value of single unit by using value of multiple units and then finding value of multiple units using value of single units is referred to as Unitary Method. Recognizing values and units is important while using unitary method to solve a problem.

For example: If 3 pencils cost 9 rupees, how much will 10 pencils cost? We can find the answer by using unitary method. One pencil will cost 3 rupees so 10 pencils will cost 30 rupees.

10 Apples = Rs 100

1 Apple = 100/10 = Rs 10

6 Apples = 10 x 6 = Rs 60

Unitary Method


Steps to Use Unitary Method

Unitary method has two steps. It includes using division and multiplication.

Let us take an example for better understanding. Suppose 5 notebooks cost 150 rupees. How much will 7 notebooks cost?

Let us first note the information we have. We know that 5 notebooks cost 150 rupees.

Step 1: First, we have to find cost of one notebook. We can do that by dividing the total cost of 5 notebooks with total number of notebooks.

If 5 notebooks cost 150 rupees, one notebook = 150/5 = 30 rupees

Now we know that one notebook costs 30 rupees.

Step 2: We need to find cost of 7 notebooks.

If one notebook costs 30 rupees, 7 notebooks = 30 x 7 = 210 rupees

So, 7 notebooks cost 210 rupees.

Also Read: 


Types of Unitary Method

[Click Here for Sample Questions]

There are 2 variations of unitary method: Direct Variation and Indirect Variation.

Direct Variation

When increase or decrease in one quantity leads to increase or decrease (respectively) in another quantity, it is direct variation. For example: if there is an increase in quantity of goods, there will be an increase in price. Another example: the amount of work done by multiple men will be more than amount of work done by one man. So, if we decrease the number of men, work done also decreases.

Indirect Variation

When there in an increase in value of one quantity, the value of another quantity decreases. When there is a decrease in value of one quantity, the value of another quantity increases. This is indirect variation. It is basically the inverse of direct variation. For instance, when we increase the speed of the vehicle, we can cover the distance in less time. So increase in speed leads to decrease in time.

Also Read: Natural Numbers and Whole Numbers Addition Subtraction and Division


Uses of Unitary Method

Unitary method has many practical applications in different areas ranging from price, distance, speed, time etc.

Some of the most common applications of unitary method are:

  • Profit and loss in business is determined using unitary method.
  • Price of a good can be evaluated using this method.
  • It helps in finding the number of people needed to finish a given amount of work
  • Time taken to cover a specific distance in a specific time can be determined using unitary method.
  • Percentage of a quantity can be calculated

Use of Unitary Method in Ratio and Proportion

Unitary method is also used to find the ratio of one quantity in relation to another.

For example: Income of Rakesh is 12000 per month and yearly income of Mahesh is 191520. They spend a total of 9960 every month; find the ratio of their savings using the unitary method.

Savings of Rakesh per month = 12000 – 9960 = 2040 Rupees

Yearly income of Mahesh = 191520 Rupees

Monthly income of Mahesh = 191520 / 12 = 15960 Rupees

Savings of Mahesh = 15960 – 9960 = 6000 Rupees

So the ratio of savings of Rakesh and Mahesh is 2040:6000 = 17:50

Also Read: 


Things to Remember

  • Unitary method is the process of finding the value of single unit by using value of multiple units and then finding the value of multiple units using value of single units.
  • There are 2 variations of unitary method: Direct Variation and Indirect Variation.
  • When increase or decrease in one quantity leads to increase or decrease (respectively) in another quantity, it is direct variation.
  • When there in an increase in value of one quantity, the value of another quantity decreases. When there is a decrease in value of one quantity, the value of another quantity increases. This is indirect variation.
  • Unitary method has many practical applications in different areas ranging from price, distance, speed, time etc.

Sample Questions

Ques. What is unitary method? (2 Marks)

Ans. The procedure of finding the value of single unit by using value of multiple units and then finding the value of multiple units using value of single units is referred to as Unitary Method. Recognizing the values and units is important while using unitary method to solve a problem. There are 2 variations of unitary method: Direct Variation and Indirect Variation.

Ques. If the weight of 24 bricks is 48 Kg, calculate the weight of 29 bricks. (2 Marks)

Ans. The weight of 24 bricks is 48 Kg

So, weight of one brick = 48/24 = 2 Kg

The weight of 29 bricks

= 29 x 2 = 58 Kg

The weight of 29 bricks is 58 Kg.

Also Read: Rationalise the Denominator

Ques. If the annual rent of a house is Rs. 108000, calculate the rent of 8 months. (2 Marks)

Ans. Annual rent of a house is Rs. 108000

Monthly rent of the house = 108000/12 = 9000 Rupees

So, the rent of 8 months

= 9000 x 8 = 72000 Rupees

The rent of 8 months is 72000 Rupees.

Ques. What are the types of unitary method? (3 Marks)

Ans. There are 2 variations of unitary method:

Direct Variation:- When increase or decrease in one quantity leads to increase or decrease (respectively) in another quantity, it is direct variation. For example, the amount of work done by multiple men will be more than amount of work done by one man. So, if we decrease the number of men, work done also decreases.

Indirect Variation:- When there in an increase in value of one quantity, the value of another quantity decreases. When there is a decrease in value of one quantity, the value of another quantity increases. This is indirect variation. It is basically the inverse of direct variation.

Ques. A bus travelling at the speed of 70 kmph covers 210 Km. How long will the same bus, travelling at the same speed, would take to cover 140 km. (2 Marks)

Ans. Time required to cover 210 Km:

Speed = Distance/Time

Time = Distance/Speed

Time = 210 / 70 = 3 hours

If 210 Km takes 3 hours,

140 Km would take: 140 x (3/210) = 2 hours

The same bus would take 2 hours to cover distance of 140 Km.

Ques. What are some practical applications of unitary method? (3 Marks)

Ans. Some practical applications of Unitary method are:

  • Profit and loss in business can determined using unitary method.
  • Percentage of a quantity can be calculated
  • Price of a good can be evaluated using this method.
  • Time taken to cover a specific distance in a specific time can be determined using unitary method.
  • It helps in finding the number of people needed to finish a given amount of work

Also Read: Sequence and Series

Ques. If 3 buses can carry 150 passengers, find out the number of passengers 7 buses can carry. (2 Marks)

Ans. 3 buses can carry 150 passengers.

So 1 bus can carry = 150/3 = 50 passengers

If 1 bus carries 50 passengers, 7 buses can carry

= 50 x 7 = 350 passengers

So, 7 buses can carry 350 passengers.

Ques. A car can run 120 Km on 12 litres of diesel, how many kilometers can it run on 6 litres of diesel? (2 Marks)

Ans. A car runs 120 Km on 12 litres.

So, 1 litre = 120/12 = 10 Km

If one litre diesel can make car run 10 Km, 6 litres diesel

= 10 x 6 = 60 Km

A car can run 60 Km on 6 litres of diesel.

Also Read: 

CBSE X Related Questions

1.

Form the pair of linear equations for the following problems and find their solution by substitution method.

(i) The difference between two numbers is 26 and one number is three times the other. Find them.

(ii) The larger of two supplementary angles exceeds the smaller by 18 degrees. Find them.

(iii) The coach of a cricket team buys 7 bats and 6 balls for Rs 3800. Later, she buys 3 bats and 5 balls for Rs 1750. Find the cost of each bat and each ball.

(iv) The taxi charges in a city consist of a fixed charge together with the charge for the distance covered. For a distance of 10 km, the charge paid is Rs 105 and for a journey of 15 km, the charge paid is Rs 155. What are the fixed charges and the charge per km? How much does a person have to pay for travelling a distance of 25 km.

(v) A fraction becomes\(\frac{ 9}{11}\), if 2 is added to both the numerator and the denominator. If, 3 is added to both the numerator and the denominator it becomes \(\frac{5}{6}\). Find the fraction.

(vi) Five years hence, the age of Jacob will be three times that of his son. Five years ago, Jacob’s age was seven times that of his son. What are their present ages?

      2.
      Which of the following are APs? If they form an AP, find the common difference d and write three more terms.
      (i) 2, 4, 8, 16, . . . .
      (ii) \(2, \frac{5}{2},3,\frac{7}{2}\), . . . .
      (iii) – 1.2, – 3.2, – 5.2, – 7.2, . . . .
      (iv) – 10, – 6, – 2, 2, . . .
      (v) 3, \(3 + \sqrt{2} , 3 + 3\sqrt{2} , 3 + 3 \sqrt{2}\) . . . .
      (vi) 0.2, 0.22, 0.222, 0.2222, . . . .
      (vii) 0, – 4, – 8, –12, . . . .
      (viii) \(\frac{-1}{2}, \frac{-1}{2}, \frac{-1}{2}, \frac{-1}{2}\), . . . .
      (ix) 1, 3, 9, 27, . . . .
      (x) a, 2a, 3a, 4a, . . . .
      (xi) a, \(a^2, a^3, a^4,\)  . . . .
      (xii) \(\sqrt{2}, \sqrt{8} , \sqrt{18} , \sqrt {32}\) . . . .
      (xiii) \(\sqrt {3}, \sqrt {6}, \sqrt {9} , \sqrt {12}\) . . . . .
      (xiv) \(1^2 , 3^2 , 5^2 , 7^2\), . . . .
      (xv) \(1^2 , 5^2, 7^2, 7^3\), . . . .

          3.

          The following frequency distribution gives the monthly consumption of electricity of 68 consumers of a locality. Find the median, mean and mode of the data and compare them

          Monthly consumption 
          (in units)

           Number of consumers

          65 - 85 

          4

          85 - 105

          5

          105 - 125

          13

          125 - 145

          20

          145 - 165

          14

          165 - 185

          8

          185 - 205

          4

              4.
              The angle of elevation of the top of a building from the foot of the tower is 30° and the angle of elevation of the top of the tower from the foot of the building is 60°. If the tower is 50 m high, find the height of the building.

                  5.
                  A 1.5 m tall boy is standing at some distance from a 30 m tall building. The angle of elevation from his eyes to the top of the building increases from 30° to 60° as he walks towards the building. Find the distance he walked towards the building.

                      6.

                      Solve the following pair of linear equations by the substitution method. 
                      (i) x + y = 14 
                          x – y = 4   

                      (ii) s – t = 3 
                          \(\frac{s}{3} + \frac{t}{2}\) =6 

                      (iii) 3x – y = 3 
                            9x – 3y = 9

                      (iv) 0.2x + 0.3y = 1.3 
                           0.4x + 0.5y = 2.3 

                      (v)\(\sqrt2x\) + \(\sqrt3y\)=0
                          \(\sqrt3x\) - \(\sqrt8y\) = 0

                      (vi) \(\frac{3x}{2} - \frac{5y}{3}\) =-2,
                          \(\frac{ x}{3} + \frac{y}{2}\) = \(\frac{ 13}{6}\)

                          Comments



                          No Comments To Show