Today I am sharing important Percentage concepts with solved examples :-
If two values are respectively x% and y% more than a third value,
Rule 1
If two values are respectively x% and y% more than a third value,
Solution :-Ques 1.
Two numbers are respectively 20% and 50% more than a third number, What percentage is the first of the second?
Ques 2.
Two numbers are respectively 30% and 40% less than the a third number .What percent is the second of the first?
Solution :-
Her our formulas would change , we will put a – sign instead of +sign.
Ques 3.
A positive number is divided by 5 instead of being multiplied by 5. What percent is the result of the required correct value?
Solution :-
Let the number be 1
Then the correct answer = 5
The incorrect answer that was obtained = 1/5
Ques 4.
A positive number is by mistake multiplied by 5 instead of being divided by 5. By what percent more or less than the correct answer is the result obtained?
Solution :-
Let the number be 1
Then the correct answer= 1/5
The incorrect answer that was obtained = 5
The result is more than the correct answer= 5-1/5=24/5
Solution :-Ques 5.
A man loses 12.5% of his money and, after spending 70% of the remainder, he is left with Rs 210. How much had he at first?
It is very easy and fast calculating method. The only thing is to remember the formula well.
Note: As his initial money is definitely more than the left money, Ther should not be any confusion in putting the larger value (100) in the numerator and the smaller value (100-12.5) in the denominator.
Solution :-Ques 6.
3.5% of income is taken as tax and 12.5% of the remaining is saved .This leaves Rs. 4,053 to spend .What is the income?
Quicker method
Rule 2
If x% of a quantity is taken by the first , y% of the remaining is taken by the second and the Z% of the remaining is taken by third person. Now if A is left in the fund, then there wasRule 3
If x% of a quantity is taken by the first , y% of the increased is added. Again z% of the increased quantity is added. Now it becomes A, Then the initial amount is given bySolution :-Ques 7.
After deducting 10% from a certain sum , and 20% from the remainder, there is 3600 left. Find the original sum
The original sum is naturally more than Rs. 3600.
Solution :-Ques 8.
A man had Rs 4800 in his locker two years ago. In the first year, he deposited 20% of the amount in his locker. In the second year, he deposited 25% of the increased amount in his locker. Find the amount at present in his locker.
The amount is certainly more than Rs 4800. And in each year, the new amount is added. So, the sum should be multiplied by
(100+20)/100 and (100+25)/100
Rule 4
Population formulaIf the original population of a town is P, and the annual increase is r%. What will be the population in n years?
Solution :-Ques 9.
If the annual increase in the population of a town is 4% and the present number of people is 15,625. What will be the population in 3 years?
Rule 5
The population of a town is P. It increases by x% during the first year, increases by y% during the second year and again increases by z% during the third year. The population after 3 years will beSolution :-Ques 10.
The population of a town is 8000.It increases by 10% during the first year and by 20% during the second year. What is the population after two years?
Rule 6
When the population of a town decreases by y% during the second year, while for the first and third year, it follows the same ( means it increases x% and z% respectively), the population after 3 years will beSolution :-Ques 11.
The population of a town is 10,000, It increases by 10% during the first year . During the second year, it decreases by 20% and increases by 30% during the third year. What is the population after 3 years?
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