Notes On Application of Percentages - CBSE Class 7 Maths
Percentages are helpful in comparison. The increase or decrease in a certain quantity can be expressed as percentage increase or decrease. Percentage increase/decrease = $\frac{\text{Amount of change (Increase or Decrease)}}{\text{Original amount or base}}$ × 100 Profit and loss Profit is the money gained on selling an item. Loss is the money lost on selling an item. If the selling price of an item is more than the cost price, then a profit is incurred. If the cost price of an item is more than the selling price, then a loss is incurred. When the cost price is equal to the selling price, it is called a no-profit no-loss situation. Profit = Selling price – Cost price Loss = Cost price – Selling price CP = SP ⇒ No Profit no Loss Profit percentage or loss percentage is always calculated on the cost price. Profit percentage = $\frac{\text{Profit}}{\text{Cost price}}$ × 100 Loss percentage = $\frac{\text{Loss}}{\text{Cost price}}$ × 100 Simple interest Interest is the fee paid as the cost of borrowing on the borrowed money. The way of calculating interest, where the principal is not changed, is known as "simple interest". As the number of years increases, interest will also increase.  If P denotes the principal, R denotes the rate of interest and T denotes the time period, then the simple interest I paid for T years is $\frac{\text{P × T × R}}{\text{100}}$. Sum that is returned at the end of the time period is called the amount (A). Amount can be obtained by adding the sum borrowed (principal) and the interest.  Amount = Principal + Interest.

#### Summary

Percentages are helpful in comparison. The increase or decrease in a certain quantity can be expressed as percentage increase or decrease. Percentage increase/decrease = $\frac{\text{Amount of change (Increase or Decrease)}}{\text{Original amount or base}}$ × 100 Profit and loss Profit is the money gained on selling an item. Loss is the money lost on selling an item. If the selling price of an item is more than the cost price, then a profit is incurred. If the cost price of an item is more than the selling price, then a loss is incurred. When the cost price is equal to the selling price, it is called a no-profit no-loss situation. Profit = Selling price – Cost price Loss = Cost price – Selling price CP = SP ⇒ No Profit no Loss Profit percentage or loss percentage is always calculated on the cost price. Profit percentage = $\frac{\text{Profit}}{\text{Cost price}}$ × 100 Loss percentage = $\frac{\text{Loss}}{\text{Cost price}}$ × 100 Simple interest Interest is the fee paid as the cost of borrowing on the borrowed money. The way of calculating interest, where the principal is not changed, is known as "simple interest". As the number of years increases, interest will also increase.  If P denotes the principal, R denotes the rate of interest and T denotes the time period, then the simple interest I paid for T years is $\frac{\text{P × T × R}}{\text{100}}$. Sum that is returned at the end of the time period is called the amount (A). Amount can be obtained by adding the sum borrowed (principal) and the interest.  Amount = Principal + Interest.

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