: Ace questions on percentage for SI exams #IndiaNEWS #Education Today Hyderabad: This article is in continuation to the last article on preparation for the Sub-Inspector of Police recruitment exam.

Ace questions on percentage for SI exams #IndiaNEWS #Education Today
Hyderabad: This article is in continuation to the last article on preparation for the Sub-Inspector of Police recruitment exam. Here are some previously asked questions and answers along with explanations on the percentage topic.
1) The population of a town is 1,54,000. It increases by 5% during the first year. During the second year it decreases by 10% and increases by 10% during the third year. Then the population of the town after three years is(SI 2016)
a) 161700 b) 160700 c) 160083 d) 170062
Ans: c
Explanation:
The population of a town = 1,54,000
The population of a town after 3 years = = 160083
∴the population of the town after 3 years is 160083.
2) A number x is increased by 30% and then decreased by 30%, then the number x is (SI 2016)
a) Does not change b) decreases by 6%
c) Increases by 6% d) decreases by 9%
Ans: d
Explanation:
Since we have given that a number is increased by 30%.
Then a number is decreased by 30%.
Let x = 30% and y = -30%
So, the net increase or decrease percent would be
Hence, there is net decrease of 9%.
3) One side of a square is increased by 20%. To maintain the same area the
other side will have to be decreased by(SI 2016)
a) 16 2/3% b) 14 2/3% c) 11 1/3% d) 14 1/3%
Ans: a
Explanation:
Suppose size of square = 100
Area= 100100= 10000
Now, 20% increase in size would be =(20% of 100)=20
New length of square = 100 20=120
To maintain the original area i. e 10000
10000= 120 x new size of another side
= 10000/120= 83. 33
So decrease must be of (100–83. 33)= 16. 66
Percentage decrease is= 16. 66% or 16 2/3%
4) Two numbers are in the ratio 5: 4. If 40% of the first number is 120, then 60% of the second number is equal to(SI 2016)
a) 124 b) 134 c) 144 d) 156
Ans: c
Explanation:
Two numbers are say 5x and 4x.
40% of 5x = 120, or
(40/100)*5x = 120
Or x = 12000/200 = 60.
Hence 60% of the second number = 0. 6*4*60 = 144
5) In an examination there were 640 boys and 360 girls. If 60% of boys and 70% of girls were successful, the percentage of failure was(SI 2016)
a) 36. 4% b) 35. 4% c) 32. 8% d) 35. 6%
Ans: a
Explanation:
Total number of students = 640 360 = 1000
Number of successful boys = 60% of 640 = 384
Number of successful girls = 70% of 360 = 252
Total number of successful students = 384 252 = 636
Number of unsuccessful students = 1000 – 636 = 364
∴required percentage= 364/1000×100=36. 4%
6) A person gave 20% of his income to his elder son, 30% of the remaining to the younger son and 10% of the balance he donated to a trust. If he is left with Rs. 10080. His income ( in rupees) is(SI 2016)
a) 50000 b) 40000 c) 30000 d) 20000
Ans: d
Explanation:
Let us assume he had Rs. x.
Finally left amount = (100 – 20)% of (100 – 30)% of (100 – 10)% of x = 10080
10080
x = 10080
x = 20,000
7) In a school, the ratio of the number of boys and girls is 3:2.