Percentage decrease formula is the measure to identify how much a variable has lost its value. The variable can either be population, cost, profit, etc. Here, the formula for percentage decrease is given along with solved examples for better understanding of the concept.
Formula for Percent Decrease
Percentage decrease formula can be obtained by simply dividing the decreased value by the original value and multiplying that with 100.
| ∴ Percent Decrease = (Decreased Value / Original Value) × 100 |
Here,
- Decreased Value = Original Value – New Value
This formula for percentage decrease will help to solve several questions. Some important questions involving this formula are given below.
Try This: Percentage Decrease Calculator
Example Questions Using Percent Decrease Formula
Example 1:
A shopkeeper used to sell a pair of pens for Rs. 25. He then reduced the price of the same pair of pens to Rs. 21. Calculate the percentage decrease in cost.
Solution:
In this question, the decrease amount is = Rs. (25 – 21) = Rs. 4
Now, the decrease in percentage = (4/ 25) × 100 = 16%
Example 2:
A fruit seller used to sell bananas for Rs. 40 per dozen. Now he reduced the cost of a dozen bananas by 10%. What is the price of a dozen bananas now?
Solution:
Let the new value for a dozen bananas be Rs. x.
Now, decrease value = Rs. (40 – x)
According to the percent decrease formula,
% D = (Decrease/ Old value) × 100
It is given that %D = 10.
So, putting these values in the equation,
10/100 = (40 – x)/40
=> 40 – x = 4
=> x = 36
So, the new price of a dozen of bananas is Rs. 36.
Example 3:
The cost of a membership card of a club was reduced by 20% and costs Rs. 550 now. What was the original price of the membership card before its cost reduced?
Solution:
Let the original cost be Rs. x
As the new cost is Rs. 550, decrease = Rs. (x – 550)
%D = decrease/original × 100
∴ (x – 550)/x = 20/100
So, 5x – 2750 = x
=> x = 687.5
Hence, the original price was Rs. 687.5.
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