Maths : Volume and Surface Areas

1) If each edge of a cube is increased by 50%, find the percentage increase in Its surface area

A) 125 %
B) 150 %
C) 112.5%
D) 110 %

Answer: A) 125%


2) How many cubes of 2cm edge can be cut out of a cube of  8cm edge

A) 16
B) 9
C) 27
D) 64

Answer : D) 64

3) Find the length of the longest pole that can be placed in a room 12 m long 8m broad and 9m high.
A) 14m
B) 15m
C) 16m
D) 17m

Answer:  D) 17 m


4) How many bricks, each measuring 25 cm x 11.25 cm x 6 cm, will be needed to build a wall of 10 m x 6 m x 22.5 cm?
A) 5600
B) 6000
C) 8000
D) 7200

Answer : C


5) A cuboid block 6 cm by 12 cm by 15 cm is cut up into an exact number of equal cubes. Find the least possible number of cubes.
A) 30
B) 40
C) 10
D) 20

Answer: B) 40

Explanation:
Volume of the block = (6 x 12 x 15)  cm^3 = 1080  cm^3
Side of the largest cube = H.C.F. of 6 cm, 12 cm, 15 cm
                                          = 3 cm.
Volume of this cube  = (3 x 3 x 3)  cm^3 = 27 cm^3
Number of cubes = 1080/27 = 40

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