Percentage- Aptitude Questions and Answers

Y is M percent of X --> (MX/100)=Y

X is N percent of Y --> (NY/100)=X

Thus, after subsitute Y's value
=>(N/100)*(M/100)*X=X
=>MN=10000

Let the original price of a egg= X
New price, 30% increased in the price => (1+30/100)X =>13X/10
according to question
9.10( 1/X - 1/(13X/10) )=3
(9.10/3)(3/13)=X
X=9.1/13

So present price of a egg i.e. new price=>13X/10
=>(13/10)(9.1/13) =>.91

% of females student =44
So % of male students=(100-44)=>56

Let the total number of students=X
then 56% of X <=> 56X/100=42
X=4200/56

Therefore total students = X => 75

Let initial price of petrol =Rs. 100 per ltr
Initial monthly consumption =100 ltr
Total monthly expenditure =100×100=Rs. 10000

New price of petrol(falls down by 20%)=Rs. 80 per ltr
Let new monthly consumption=x ltr
New monthly expenditure =80*x

to keep monthly expenditure remain constant⇒ 10000=80*x
⇒x=125

i.e., increase in consumption=25%

The height of a tree after n yeras , if it increases at the rate of R% per annum= P [1+(R/100)]ⁿ
Thus,
The height of the tree after three years= 800 [1+(10/100)]³
=> 800 [11/10]³
=> .8*11*11*11
=> 1064.8 cm

Let original consumption = 100 kg and new consumption = x kg,
So, 100*50 = x*75
x=200/3
Reduction in consumption (100-200/3)= 100/3 = 33(1/3)%

Let x be the maximum marks,

Then (30% of x)+8 = (35% of x)-12

3*x/10 + 8 = 7*x/20 - 12
3*x + 80 = (7*x - 240)/2

6*x + 160 = 7*x -240
Hence,Minimum marks x=400

Let a original number is = 100
New number, increased by 30% = 100 + (30% of 100) = 130
Now it is reduced by 30% = 130 - (30% of 130) = 91

that means , in net it is 100 - 91 = 9% decreasing

Or
If something increased by x% and reduced by x% then net effect will be loss of (x/10)² %
= (30/10)²
= 9 %

Let the boy had Rs.x
Money given to his companion = 80% of x = 4x/5
Remaining money = x - 4x/5 = x/5
Money given to another companion = (6/100)*(x/5) = 3x/250
Remaining money => x/5 - 3x/250 = 94/100 (in rupees)
so 47x/250 = 94/100
x = 94*250/100*47
x = 5 (in rupees)

Let initial price of petrol =Rs. 100 per ltr
Initial monthly consumption =100 ltr
Total monthly expenditure =100×100=Rs. 10000

New price of petrol(increased by 25%)=Rs. 125 per ltr
Let new monthly consumption=x ltr
New monthly expenditure =125*x

to keep monthly expenditure remain constant⇒ 10000=125*x
⇒x=80

i.e., reducedtion in consumption=20%

Let initial price of Sugar=Rs. 100 per kg
Initial monthly consumption =100 kg
Total monthly expenditure =100×100=Rs. 10000

New price of Sugar(falls down by 25%)=Rs. 75 per kg
Let new monthly consumption=x kg
New monthly expenditure =75*x

to keep monthly expenditure remain constant⇒ 10000=75*x
⇒x=133(1/3)

i.e., increase in consumption=33(1/3)%

Let 100 was the visitors.
On the ticket price 12 the total collection = 12 *100 = 1200

After decreased in price , let it be X.
New visitors= 100 + 80% of 100 =>180
New income, total income after 20% increased = 1200 + 20% of 1200=>1440

Therefore, New collection = X * 180 = 1440
=> X = 1440/180

thus, Price of each ticket ,X = 8

Let 100 kg of hematite be obtained then 20% of it get wasted that means 80 kg of ore remains.
Pure iron = 25% of remaining ore = 80*25/100 = 20 kg.
20 kg pure Iron is obtained from 100 of hematite.
1 kg pure Iron is obtained from = 100/20 hematite;
Then, 80000 kg pure Iron is obtained from = (100/20)*80000 = 400000 kg hematite.

Number of men who can read and write = 150000 × (98 ÷ 100) =147000
Number of men and women who can read and write =294000 × (53 ÷ 100) =155820
Number of women who can read and write 155820 - 147000 = 8820
Thus, out of 144000 women 8820 can read and write.
Required percentage = (8820 × 100) ⁄ 144000 %= 6.125

The difference in percentage = 68% - 43% = 25%
i.e. 25% of a number = 280
therefore, the number = 280 × 100 / 25
=> 1120

If the present population of the town is P now and it increases at the rate of R% per annum, then:
Population after n yeras = P [1+(R/100)]ⁿ

The population after 2 years= 100000 [1+(5/100)]²
= 100000*21/20*21/20
= 110250

Let cost of each item = Rs.100 & sale = 100 item .
Revenue = Rs.(100*100) = Rs.10000

New cost per item= Rs.80 and New sale = 130 item
New Revenue = Rs.(80*130) = 10400

Percent Change =(new - old)/(old)= (400/10000)*100 = 4%