What’s the percentage of your increasing score?
Hyderabad: This article is in continuation to the last article focusing on the percentage topic.
Here are some practice questions along with solutions that will help you in your preparation for the State government recruitment jobs.
2. If each edge of a cube is increased by 40%, the percentage increase in its surface area is
a) 40% b) 60% c) 80% d) 96%
Ans: d
Solution: 40% = 40/100 = 2/5
Surface area = 6a²
Edge –>; 5 : 7
Surface area –>; 25 : 49
24/25 × 100% = 96%
3. The percentage increase in the surface area of a cube when each side is doubled is?
a) 50% b) 150% c) 200% d) 300%
Ans: d
Solution: 100% = 100/100 = 1
Surface area = 6a²
Edge –>; 1 : 2
Surface area –>; 1 : 4
3/1 × 100% = 300%
4. If each side of a cube is decreased by 20%, the percentage decrease in its surface area is?
a) 20% b) 25% c) 35% d) 36%
Ans: d
Solution: 20% = -200/100 = -1/5
Surface area = 6a²
Side –>; 5 : 4
Surface area –>; 25 : 16
-9/25 × 100% = -36%
5. If each side of a cube is increased by 10%, then the percentage increase in its volume is?
a) 33.1% b) 33.5% c) 30% d) 32.5%
Ans: a
Solution: 10% = 10/100 = 1/10
Volume = (Side)³
Side –>; 10 : 11
Volume –>; 10³ : 11³
1000 : 1331
331/1000 × 100% = 33.1%
6. If each side of a cube is doubled, then the percentage increase in its volume is?
a) 100% b) 400% c) 700% d) 800%
Ans: c
Solution: 100% = 100/100= 1/1
Volume = (Side)³
Side –>; 1 : 2
Volume –>; 1³ : 2³
1 : 8
7/1 × 100% = 700%
7. If each side of a cube is decreased by 20%, then the percentage decrease in its volume is?
a) 44% b) 44.5% c) 48.8% d) 48%
Ans: c
Solution: 20% = -20/100 = -1/5
Volume = (Side)³
Side –>; 5 : 4
Volume –>; 5³ : 4³
125 : 64
– 61/125 × 100% = – 48.8%
8. If the length, breadth and height of a cuboid increased by 10%, 20% and 30% respectively, then the volume of a cuboid is increased by?
a) 104% b) 114% c) 124% d) 134%
Ans: d
Solution: 10% = 10/20 = 1/2, 20% = 20/100 = 1/5, 30% = 30/100 = 3/10
Volume = length × breadth × height
Length –>; 2 : 3
Breadth –>; 5 : 6
Height –>; 10 : 13
Volume –>; 2 × 5 × 10 : 3 × 6 × 13
50 : 117
67/50 × 100% = 134%
9. If the length of a cuboid is increased by 10%, breadth is increased by 20%, and the height is decreased by 20%, then the volume of a cuboid is increased/ decreased by?
a) 5.6% increases b) 5.6% decreases c) 6.5% increases d) 6.5% decreases
Ans: a
Solution: 10% = 10/100 = 1/10, 20% = 20/100 = 1/5, 20% = -20/100 = -1/5
Volume = length × breadth × height
Length –>; 10 : 11
Breadth –>; 5 : 6
Height –>; 5 : 4
Volume –>; 10 × 5 × 5 : 11 × 6 × 4
125 : 132
7/125 × 100% = 5.6%
= 5.6% increases
10. In a cuboid, if the length is increased by 63.63% and the breadth is decreased by 41 2/3%, then by how much percentage should the height be changed so that the volume remains constant?
a) 4.5% b) 4.76% c) 5% d) 5.76%
Ans: b
Solution: 63.63% = 7/11, 41 2/3% = -5/12
Volume = length × breadth × height
Length –>; 11 : 18
Breadth –>; 12 : 7
Height –>; 18×7 : 11×12 (volume remains constant)
21 : 22
1/21 × 100% = 4.76%
