Published: Published Date - 11:48 PM, Mon - 11 July 22
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 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% 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% 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 Volume = length × breadth × height Length –>; 2 : 3 Height –>; 10 : 13 Volume –>; 2 × 5 × 10 : 3 × 6 × 13 50 : 117 67/50 × 100% = 134% 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 a) 4.5% b) 4.76% c) 5% d) 5.76% Ans: b 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% No worries! We‘ve got your back. Try BYJU‘S free classes today! No worries! We‘ve got your back. Try BYJU‘S free classes today! Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses No worries! We‘ve got your back. Try BYJU‘S free classes today!
Hello Prasad ! Formula for Volume of cuboid is , (length × breadth × height) cubic units. So , if length is increased by 20% which means new length is 1.2 time of old length , similarly , new breadth will become 1.1 time more and height will become 0.95 times of old height , as it decreased. So now , new volume will become , 1.2 * length × 1.1*breadth × 0.95*height , 1.254 * length × breadth × height , Which means it get increased by 25.4 % Hope it helps ! Given: The ratio of length, breadth and height of cuboid was 5 : 4 : 3 The length of cuboid is increased by 20% Breadth is increased by 25% And height is increased by 33.33% The total surface area of cuboid is increased by 216 cm2 Calculation: Let the ratio be x So, length of cuboid = 5x So, breadth of cuboid = 4x And height of cuboid = 3x So, the total surface area of cuboid = 2 × (12x2 + 20x2 + 15x2) = 94x2 After increment Length of cuboid = 5x × 120% = 6x Breadth of cuboid = 4x × 125% = 5x And height of cuboid = 3x × 133.34% = 4x So, new total surface area = 2 × (30x2 + 20x2 + 24x2) = 148x2 Now, according to question 148x2 – 94x2 = 216 ⇒ 54x2 = 216 ⇒ x2 = 4 So, x = 2 So, new length, breadth and height of cuboid are 12, 10 and 8 So, volume of new cuboid = 12 × 10 × 8 ∴ 960 cm3 |