Few weeks back I shared how to make application of Percentages concept. Today I am sharing examples to illustrate the usage of this concept.
Question 1.Salary of A is 75% of B’s salary. Salary of A is increased by 40% but salary of B is increased by only 10%. Whose salary is more and by what percent?
Salary of A = 75% of Salary of B
Question 2.The price of a commodity increases by 25% and therefore a house wife reduces the quantity purchased by certain percentage in order to maintain expenditure. By what percentage should she reduce the quantity purchased ?
The short cut could be made on the basis that
Price ∝ 1/Quantity
Which means if you reduce the price , the quantity will increase and vice-versa, so our formula would be :
Question 3.The price of a commodity increases by 25%. Find out the reduction in quantity such that the expenditure is allowed to increase by 20%?
Now again let the price = 100, Quantity =100
Expenditure =100 X 100= 10000
New Price =125, New Quantity =?
New Expenditure =10000+20%of 10000=12000
New Expenditure= New Price X New Quantity
12000 = 125 X New Quantity
New Quantity = 12000/125= 96
Required reduction% in the quantity = (100-96)/100 X 100 =4%
Question 4.The price of a commodity increases by 20% and expenditure is allowed to increase by 15%. What changes would occur in the quantity ?
Question 5.The price of an apple reduce by 10% and thus enables a person to buy 10 more apples for Rs. 50. Find out :
- New price
- Old Price
- New Quantity
- Old Quantity
Let us say, initially he is able to buy m apples for Rs.50.
Rs.50 = m apples
Rs. 50 = (m+10) apples
Now we can see that
⇒ Earlier in Rs. 50 , 90 apples could be bought
Now in Rs. 50, 90+10=100 apples could be bought. which clearly shows that the price has dropped
New price = Rs. 50/100
Old price = Rs. 50/90
Now let us learn a quick way
The person has got = Rs 50
The price reduces by 10 % that means he could save 10% of what he has in his pocket.
He could buy the apples in Rs 45 and can save Rs 5, but instead of saving, he is buying 10 apples for Rs 5
⇒ Rs. 5 = 10 apples
Rs. 1 = 2 apples which means Rs 50 = 100 apples
The new price of one apple = Rs.0.5
Earlier Rs 50 = 100-10 = 90 apples
The old price per apple = 50/90= Rs. 0.55
So this was another method to deal with such questions.
Question 6.A container has got 130 liters of water which has 15% salt. From this container some of the water has got evaporated and after evaporation, the salt strength in the container is now 20%. Find out how much water evaporated from the container.
Solution - Let the water evaporated= m liter