(Q1)The population of a town increases by 5% every year. If the present population is 9261, The population 3 Years ago was.

Solution: F.Q=I.Q×M.F

Where I.Q=Initial Quantity

F.Q=Final Quantity

M.F=Multiplying Factor

Now

F.Q=I.Q×M.F

9261=I.Q×(105/100)×(105/100)×(105/100)

I.Q=(9261×100×100×100)/(105×105×105)

=8000 Ans

CONCEPT:[इस Type के Question को Solve करते Time आपलोगो को सिर्फ इन बातों पर ध्यान रखना है Question में After n Years का value निकालने के लिए कह रहा है या n Years Ago का | (1)यदि Question में After n Years का value निकालने के लिए कह रहा हो तो Present value जो Question में दिया होगा वह Initial Quantity होगा| (2) यदि Question में  n Years Ago का value निकालने के लिए कह रहा हो तो Present value जो Question में दिया होगा वह Final Quantity होगा|]

(Q2)The present population of a city is 180000. If it increases at the rate of 10%per annum, its population after 2 years will be.

Solution: F.Q=I.Q×M.F

F.Q=180000×(110/100)×(110/100)

=217800 Ans.

(Q3)The present price of a scooter is 7290. If its value decreases every year by 10%, then its value after 3 years back was.

Solution: F.Q=I.Q×M.F

7290=I.Q×(90/100)×(90/100)×(90/100)

∴ I.Q=(7290×100×100×100)/(90×90×90)

=10000 Ans.

(Q4)In a factory, the production of cycles rose to 48,400 from 40,000 in 2 years. The rate of growth per annum is.

Solution: Let rate of growth=x%

F.Q=I.Q×M.F

48,400=40000×((100+x)/100)×(100+x)/100

48,400/4=(100+x)²

12100=(100+x)²

(110)²=(100+x)²

100+x=110

∴ x=10% Ans

(Q5)The population of a village was 9800. In a year with the increase in the population of males by 8% and that of females by 5%, the population of the village become 10458.What was the number of males in the village before increase?

Solution:Let the number of males=x

∴ number of females=9800-x

x×(108/100)+(9800-x)×(105/100)=10458

=>108x+9800×105-105x=1045800

=>3x=1045800-1029000

=16800

∴ x=16800/3

=5600 Ans.

Percentage Shortcut Tricks Bank PO SSC Railway Exams type-9.1.

(Q1)A large watermelon weighs 20kg with 96% of its weight being water. It is allowed to stand in the sun and some of the water evaporates so that only 95% of its weight is water.Its reduced weight will be:

Solution:

Weight of fresh watermelon=20Kg

the weight of fresh pulp=20×(4/100)

=0.8Kg

Now,

Concept:[watermelon में से water सूखेगा न कि pulp. pulp तो always same ही रहेगा चाहे Fresh हो या Dry ]

so,

5%=0.8Kg

1%=0.8/5 Kg

∴ 100%=(0.8/5)×100 Kg

=16 Kg Ans.

(Q2)Fresh grapes contain 80% water while Dry grapes contain 10% water. If the weight of dry grapes is 500Kg then what is its total weight when it is fresh.

Solution:

Weight of Dry grapes=500Kg

the weight of Dry pulp=500×(90/100)

=450Kg

Now,

Concept:[Grapes में से water सूखेगा न कि pulp. pulp तो always same ही रहेगा चाहे Fresh हो या Dry ]

so,

20%=450Kg

1%=450/20 Kg

∴ 100%=(450/20)×100 Kg

=2250 Kg Ans.