Problems on Volumes and Surface Area
Q1. Find the volume and surface area of a cuboid 10m long, 8m broad and 4m high ?
(a) 256m2
(b) 284m2
(c) 304m2
(d) 326m2
Answer: (c) 304m2
Here l = 10m b = 8m h = 4m
∴ volume = l X b X h
= 10 X 8 X 4 m3 = 320m3
Surface area = 2 (lb + bh + hl)
= 2 (10X8 + 8X4 + 4X10)m2
= 2(80 + 32 + 40)m2
= 2 X 152 m2
= 304m2
Q2. The surface area of a cube is 216m2. Find its volume.
(a) 188m3
(b) 204m3
(c) 216m3
(d) 226m3
Answer: (c) 216m3
Given that 6a2 = 216
⇒ a2 = 36
⇒ a2 = 62
⇒ a = 6m
∴ Volume = a3
= 63m3
= 216m3
Q3. Find the volume and the surface area of a sphere of diameter 14 cm
(a) 116 cm2
(b) 332 cm2
(c) 498 cm2
(d) 616 cm2
Answer: (d) 616 cm2
Here r = 14/2 cm = 7 cm
∴ Volume = | 4 | π r3 |
3 |
= | 4 | X | 22 | X 7 X 7 X 7 cm3 |
3 | 7 |
= 1437.33 cm3
Surface Area = 4π r2
= 4 X | 22 | X 72 cm2 |
7 |
= 616 cm2
Q4. The length of the longest pole that can be kept in a room 5m long, 4m broad and 2m height is
(a) 3√ 5 m
(b) 4√ 5 m
(c) 5√ 5 m
(d) 7√ 5 m
Answer: (a) 3√ 5 m
Required length = √ l2+b2+h2
=√52+42+22 m
= √ 25+16+4 m = 3√ 5 m
Q5. A rectangular water reservoir contains 54000 liters of water. If the length of reservoir is 9m and breadth is 4m, then the depth of the reservoir is
(a) 1.3 m
(b) 1.5 m
(c) 2.2 m
(d) 2.3 m
Answer: (b) 1.5 m
Volume of the reservoir = 54000 liters
⇒ l X b X h = 54 m3
⇒ 9m X 4m X h = 54 m3
⇒ h = 54/(9X4) = 1.5 m
Q6. What part of a ditch 48m long, 16.5m broad and 4m deep can be filled by the earth got by digging a cylindrical tunnel of diameter 4m and length 56m ?
(a) 2/7
(b) 2/9
(c) 3/5
(d) 3/7
Answer: (b) 2/9
Volume of the ditch = (48 X 16.5 X 4) m3 = 3168 m3
Volume of earth dug out as a tunnel = π r2h = (22/7) X 2 X 2 X 56 m3 = 704 m3
∴ Required Part = 704/3168 = 2/9
Q7. The product of the areas of three adjacent faces of a rectangular box is equal to
(a) volume of the box
(b) twice the volume of the box
(c) the square of the volume of the box
(d) cube root of the volume of the box
Answer: (c) the square of the volume of the box
Product of the areas of three adjacent faces = lb X bh X hl = l2b2h2 = (lbh)2 = v2 = volume2
∴ square of the volume of the box
Q8. The surface area of a (12cm X 5cm X 3cm) brick is
(a) 135 cm2
(b) 196 cm2
(c) 222 cm2
(d) 248 cm2
Answer: (c) 222 cm2
Here l = 12 cm b = 5 cm h = 3 cm
∴ Surface Area = 2 (lb + bh + hl)
= 2 (12X5 + 5X3 + 3X12) cm2
= 2 X 111 cm2 = 222 cm2
Q9. If the areas of three adjacent faces of a cuboid are x, y, z respectively, then the volume of the cuboid is
(a) xyz
(b) (xyz)2
(c) xy/z
(d) √ xyz
Answer: (d) √ xyz
Here l X b = x
b X h = y
h X l = z
Now xyz = lb X bh X hl
⇒ xyz = l2b2h2
⇒ xyz = (lbh)2
⇒ lbh = √ xyz
⇒ volume = √ xyz
Q10. The diagonal of a cube measures 5√ 3 cm. Its volume is
(a) 102 cm3
(b) 105 cm3
(c) 111 cm3
(d) 125 cm3
Answer: (d) 125 cm3
Given √ 3a = 5√ 3
⇒ a = 5 cm
∴ Volume = 5 X 5 X 5 cm3 = 125 cm3
Practice Test Exam