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Class 7th Science
Class 7th Math
Online Class For 7th Standard Students (CBSE)
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Comparing Quantities Class 7 Notes: Chapter 8

Prices related to an item

  • Prices related to an item are: (i) Selling price
    (ii) Cost price
  • Selling price (SP) is the price at which a product is sold out.
  • Cost price (CP) is the buying price of an item.
  • Profit = Selling price – Cost price
  • Loss = Cost price – Selling price
  • If SP > CP , then it is profit.
  • If SP = CP , then it is neither profit nor loss.
  • If CP > SP , then it is loss.

Finding the profit or loss percentage

Comparing Quantities : Introduction

  • To compare two quantities, the units must be the same.
  • Examples:
    (i) Joe’s height is 150 cm and Tom’s is 100 cm.
    Ratio of Joe’s height to Tom’s height would be Joe’s height : Tom’s height.
    = 150 : 100 = 3: 2
    (ii) Ratio of 3 km to 30 m is 3 km : 30 m.
    = 3000 m : 30 m
    = 300 : 1


  • Ratio is a relation between two quantities showing the number of times one value contains or is contained within the other.
  • Example: If there are four girls and seven boys in a class, then the ratio of number of girls to number of boys is 4:7.

Equivalent Ratios

  • By multiplying numerator and denominator of a rational number by a non zero integer, we obtain another rational number equivalent to the given rational number. These are called equivalent fractions.
  • Example:1/3=1/3×2/2=2/6 and 1/3 are equivalent fractions.


  • If two ratios are equal, then they are said to be in proportion.
  • Symbol “::” or “=” is used to equate the two ratios.
  • Example: (i) Ratios 2:3 and 6:9 are equal. They can be represented as 2:3 :: 6:9 or 2:3 = 6:9.
    (ii) Ratios 1:2 and x:4 are in proportion.



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