Comparing Quantities Class 7 Notes Maths | StudyTution

  • To compare two quantities, their units must be the same.
  • Two ratios can be compared by converting them into like fractions.
  • If the two fractions are equal, we say that the two given ratios are equivalent.
  • If two ratios are equivalent (or equal), then the involved four quantities are said to be in proportion.
  • One of the ways of comparing quantities is percentage.
  • Per cent is derived from Latin word ‘per centum’ meaning ‘per hundred’.
  • Percent is represented by the symbol % and means hundredth too.
  • Fractions can be converted into percentages and vice-versa.
  •  Decimals can also be converted into percentages and vice-versa.
  • The buying price of any item is known as its cost price.
  • It is written in short as CP.
  • The price at which an item is sold, is known as its selling price or in short SP.
  • If CP < SP, then a profit is made and Profit = SP – CP.
  • If CP = SP, there is no profit or loss.
  •  If CP > SP, then a loss is made and Loss = CP – SP.
  • Profit per cent = Profit / CP ×100
  • Loss per cent = Loss/CP ×100
  • ‘Principal’ P, means the borrowed money.
  • The extra money paid by borrower for using borrowed money for given time is called ‘Interest’ I.
  • The period for which the money is borrowed is called ‘Time Period’ T.
  • To determine Interest to be paid, we have ‘Rate of Interest’.
  • Rate of Interest is generally given in per cent per year.
  • On a principal of  P at R % rate of interest per year, the interest (simple) I paid for T years is given by
    P× R × T / 100 =I
  • The total money paid alongwith interest or principal P is called amount (A). Thus A = P + I.
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