Percentage Tricks With Examples Part-2

1.  If the price of any foodstuff is decreased by 'a%' then the consumption of it will be increased by % so that the expense of this item is remaining same. 

The price of tea is decreased by 15%. How much % consumption of sugar is increased so that the expenditure of sugar is same?


2. If a number is increase/ decrease by X% and then increase/ decrease by Y% so 

If a number is increased by 10% and then decreased by 5%. Find the total % change in that number.


Some more important Examples:

Example 1.  

20% of a number is 60 less than three-fifth of that number. Find that number.
Solution: x×3/5 - x×20% = 60
x×3/5 - x×1/5 =60

Example 2.

The length of rectangular is increased by 8% while the width is increased by 10%. What is the % change in this area?


Example 3.

Mohan gave 40% of his money to his wife and gave 20% of the remaining money to his daughter and he donated half of the amount he left and now he has only 1500 rs. How much money did Mohan have initially?
Let the total money= x

X=6250 rs.

Example 4. 

In the three sided election A gets 12% of the total votes and remain on 3rd position, B gets 46% of votes and he wins the election by 1200 votes, C remains on 2nd position. Find the total votes.
Let total votes= X

12% 46% 42%
Total votes = 30000

Example 5.

Two numbers are respectively 20% and 35% more than 3rd number. 2nd number is how much % more than 1st.
3rd number= 100, 1st number= 120, 2nd number= 135


Example 6.

In an examination 33% of total marks are passing marks. 1 candidate gets 150 marks and failed by 48 marks. Find the total marks.
Total passing marks= 150+45 =198
33% = 198
100% = 600
Total marks= 600

Example 7.

In an examination 35% of the total marks are passing marks. 1 candidate got 120 marks and failed by 5% marks. Find the passing marks.
Candidate got 35%- 5%
30% = 120
100% = 400

Example 8.

In an examination 1 candidate got 30% marks and failed by 40 marks another candidate secure 40% marks and got 40 marks more than the passing marks. Find the passing marks.
X×30%+40= X×40%-40
X×40%-X×30% = 40+40
Passing marks = 800×30% + 40
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