Students can go through AP 7th Class Maths Notes Chapter 5 Lines and Angles to understand and remember the concepts easily.
Class 7 Maths Chapter 5 Notes Lines and Angles
→ Percent is derived from Latin word “per centum” meaning “per hundred”.
→ Percent is represented by the symbol % and means hundredths too.
→ 2% means 2 out of hundred.
→ 1% = \(\frac{1}{100}\) = 0.01
→ Percentages are numerators of fractions with denominator 100.
→ 50% = \(\frac{1}{2}\)
→ \(\frac{1}{3}\) = 33\(\frac{1}{3}\)%
→ \(\frac{5}{4}\) = 125%
→ 0.75 = 75%
→ 0.2 = 20%
→ 3% means 3 parts out of 100.
→ Comparision of two quantities is called RATIO.
→ Ratio has no units.
→ Percentage increase = \(\frac{\text { Amount of change }}{\text { Original amout }}\) × 100
→ The buying price of any item is known as its cost price, written as CP.
→ The price at which you sell is known as the selling price, written as SP.
→ Profit = SP – CP
→ Loss = CP – SP
→ If SP > CP, then we get profit
→ If SP < CP, then we get loss
→ Profit percentage = \(\frac{\text { Profit }}{\mathrm{CP}}\) × 100
→ Loss percentage = \(\frac{\text { Loss }}{\mathrm{CP}}\) × 100
→ Loss (or) Profit is always calculated on CP only.
→ The money we borrow from others is called sum (or) principal.
→ The money taken from others should be returned to them with extra amount in a certain period is called INTEREST.
→ Amount = Principal + Interest.
→ Interest is generally given in percent for a period of one year.
→ If the principal is ‘P’, rate of interest ‘R’ and T is the time period and I is the
interest then I = \(\frac{\text { PTR }}{100}\).
→ Amount, A = P + I.
→ P = \(\frac{100 \mathrm{I}}{\mathrm{TR}}\)
→ T = \(\frac{100 \mathrm{I}}{\mathrm{PR}}\)
→ R = \(\frac{100 \mathrm{I}}{\mathrm{PT}}\)
→ Decimals too can be converted to percentages and vice-versa.
→ \(\frac{1}{4}\) = 25%
→ 0.25 = 25%
→ Percentages are widely used in our daily life.
a) We have learnt to find exact number when a certain percent of the total quantity is given.
b) When parts of a quantity are given to us as ratios, we have seen how to convert them to percentages.
c) The increase or decrease in a certain quantity can also be expressed as percentage.
d) The profit or loss incurred in a certain transaction can be expressed in terms of percentages.
e) While computing interest on an amount borrowed, the rate of interest is given in terms of per cents. For example, ₹ 800 borrowed for 3 years at 12% per annum.