Aptitude - Volume and Surface Area
Overview Exercise "Everything you can imagine is real."
- Pablo Picasso
11.
The curved surface area of a cylindrical pillar is 264 m2 and its volume is 924 m3 . Find the ratio of its diameter to its height.
12.
A cistern of capacity 8000 litres measures externally 3.3 m by 2.6 m by 1.1 m and its walls are 5 cm thick. The thickness of the bottom is:
Answer: A
Explanation:
Let the thickness of the bottom be x cm.
Then, [(330 - 10) x (260 - 10) x (110 - x )] = 8000 x 1000
x ) = 8000 x 1000
x ) =8000 x 1000
= 100
320 x 250
x = 10 cm = 1 dm.
13.
What is the total surface area of a right circular cone of height 14 cm and base radius 7 cm?
A. 344.35 cm2 B. 462 cm2 C. 498.35 cm2 D. None of these
Answer: E
Explanation:
h = 14 cm, r = 7 cm.
So, l = (7)2 + (14)2 = 245 = 75 cm.
= rl + r 2
=
22
x 7 x 75 +
22
x 7 x 7
2
7
7
= [154(5 + 1)] cm2
= (154 x 3.236) cm2
= 498.35 cm2 .
14.
A large cube is formed from the material obtained by melting three smaller cubes of 3, 4 and 5 cm side. What is the ratio of the total surface areas of the smaller cubes and the large cube?
Answer: C
Explanation:
Volume of the large cube = (33 + 43 + 53 ) = 216 cm3 .
Let the edge of the large cube be a .
So, a 3 = 216 a = 6 cm.
6 x (32 + 42 + 52 )
=
50
= 25 : 18.
6 x 62
36
15.
How many bricks, each measuring 25 cm x 11.25 cm x 6 cm, will be needed to build a wall of 8 m x 6 m x 22.5 cm?
Answer: B
Explanation:
Number of bricks =
Volume of the wall
=
800 x 600 x 22.5
= 6400.
Volume of 1 brick
25 x 11.25 x 6
r2h
r =
Required ratio =