Q: Find the percentage change, when a number is changed from: 80 to 100 .

Original number =80 New number =100 ,Change =(100-80)=20 \therefore Percentage change (increase) =\dfrac {20}{80}\times 100=25\%

Q: The students strength of a school was 840 Last year. This year, there is an increase of 10% Find the present strength of students.

Present student strength = 840 + 840\times\dfrac{10}{100} = 840 \times \dfrac{110}{100} = 924

Q: By what percentage will the area of a square change if its side increases by 10\% ?

Let the side of square is 100 m Then area of square = 100\times 100=10000 m^{2} If side increased 10 % the side = 100+10=110 m Then area of new square = 110\times 110=12100 m^{2} So difference area of new and old square = 12100-10000=2100 sq m So % change area of new and old square= \cfrac{2100}{10000}\times 100=21%

Q: Find the percentage change, when a number is changed from: 100 to 80 .

Original number =100 New number =80 ,Change =(100-80)=20 \therefore Percentage change (decrease) =\dfrac {20}{100}\times 100=20\%

Question 1

Find the percentage change, when a number is changed from: 6.25  to  7.50 .

Accepted Answer

Original number  =6.25 New number  =7.50 ,Change (increase)  =(7.50-6.25)=1.25 	herefore   Percentage change (increase) =\dfrac {1.25}{6.25}	imes 100=20\%

Question 2

Find the percentage change, when a number is changed from: 80  to  100 .

Accepted Answer

Original number  =80 New number  =100 ,Change  =(100-80)=20 	herefore   Percentage change (increase) =\dfrac {20}{80}	imes 100=25\%

Question 3

The population of a town increased from 4000 to 6000. Find the percentage of increase.

Accepted Answer

Percentage increase in population =  \dfrac{(6000-4000)}{4000}	imes 100 = 50\%

Question 4

A number is first increased by 20% and then reduced by 20%. What would be the percentage change in the number?

Accepted Answer

Let the number be  100 20\%  increase in  100 = 100 + \dfrac{20}{100}	imes 100 = 120 20\%  decrease in  120 = 120 - 120	imes \dfrac{20}{100} = 96 	herefore  change in number  = \dfrac{(96-100)}{100}	imes 100 = -4\% Hence, there is a decrease in number of  4\%

Question 5

A number is increased from  125  to  150 , find the percentage increase.

Accepted Answer

Original value  =125 New value  =150 Increase  =(150-125)=25 Increase  \% =\dfrac {25}{125}	imes 100=20\%

Question 6

The students strength of a school was 840 Last year. This year, there is an increase of 10% Find the present strength of students.

Accepted Answer

Present student strength =  840 + 840	imes\dfrac{10}{100}                                            =  840 	imes \dfrac{110}{100}                                            = 924

Question 7

By what percentage will the area of a square change if its side increases by  10\% ?

Accepted Answer

Let the side of square is  100 m  Then area of square = 100	imes 100=10000 m^{2} If side increased  10 % the side = 100+10=110 m Then area of new  square = 110	imes 110=12100 m^{2} So difference area of new and old square = 12100-10000=2100 sq m So % change  area of new and old square= \cfrac{2100}{10000}	imes 100=21%

Question 8

The monthly salary of a person gets increased by 5% thereby becoming Rs. 15, 120 per annum. What was his earlier salary per month?

Accepted Answer

Let earlier the annual salary of the person was  Rs. x After an increase of  5\%  his salary becomes  Rs. 15120 	herefore 15120 = x +x	imes \dfrac{5}{100} \Rightarrow 15120 = x	imes\dfrac{105}{100} \Rightarrow x = 14400 	herefore  the monthly salary was  \dfrac{Rs. 14400}{12} = Rs. 1200

Question 9

A number is decreased from  125  to  100 , find the percentage decrease.

Accepted Answer

Original value  =125 New value  =100 Increase  =(125-100)=25 Decrease  \% =\dfrac {25}{125}	imes 100=20\%

Question 10

Find the percentage change, when a number is changed from: 100  to  80 .

Accepted Answer

Original number  =100 New number  =80 ,Change  =(100-80)=20 	herefore   Percentage change (decrease) =\dfrac {20}{100}	imes 100=20\%

Important questions on Increase And Decrease In Percentage

Find the percentage change, when a number is changed from:
$6.25$ to $7.50$ .

Find the percentage change, when a number is changed from:
$80$ to $100$ .

The population of a town increased from 4000 to 6000. Find the percentage of increase.

50%

30%

20%

40%

A number is first increased by 20% and then reduced by 20%. What would be the percentage change in the number?

0

2

4

6

A number is increased from $125$ to $150$ , find the percentage increase.

The students strength of a school was 840 Last year. This year, there is an increase of 10% Find the present strength of students.

824

848

924

948

By what percentage will the area of a square change if its side increases by $10 %$ ?

The monthly salary of a person gets increased by 5% thereby becoming Rs. 15, 120 per annum. What was his earlier salary per month?

Rs. 1200

Rs. 1100

Rs. 1000

Rs. 700

A number is decreased from $125$ to $100$ , find the percentage decrease.

Find the percentage change, when a number is changed from:
$100$ to $80$ .

More important questions