Module -1
Let us discuss , if the problems is based on percentage change.
1. If the salary of person increased by 10% and then decreased by 10% , what is the overall percentage change in the salary?
Ans :
Let us assume the salary of person is 100% , then it is increased by 10% so it becomes 110%.
Now it is decreased by 10% from 110 that is 11, so
110 - 11 = 99
Initial salary is 100% , now the salary is 99% that is 1% change in the percentage.
2. If the cost price of an article is 100 , while selling he increased the cost price by 20% and then decreased 20% . what is profit or loss percentage. ?
Ans :
Let us assume the cost price of an article is 100% that is 100, then it is increased by 20% so it becomes 120%.
Now it is decreased by 20% from 120 that is 24, so
120 - 24 = 96
Initial cost price of an article is 100% , now it becomes is 96% that is 4% loss to that person .
3. If the salary of person increased by 30% and then decreased by 30% , what is the overall percentage change in the salary?
Ans :
Let us assume the salary of person is 100% , then it is increased by 30% so it becomes 130%.
Now it is decreased by 30% from 130 that is 39, so
130 - 39 = 91
Initial salary is 100% , now the salary is 91% that is 9% change in the percentage.
Conclusion :
- For `N%` increased and `N%` decreased then overall change is (N/10)^2 decreased.
- If percentage increased and then decreased or decreased and then increased then output will be same.
Example :
- 10 % increased and 10% decreased , then overall change is 1% decreased.
- 20 % increased and 20% decreased , then overall change is 4% decreased.
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