100+ Volume and Surface Area Aptitude Questions & Answers - 2

Question: 6

A cone of height 7 cm and base radius cm is carved from a rectangular block of wood 10 cm x 5 cm x 2 cm. the percentage of wood wasted is

(A) 32%

(B) 34%

(C) 46%

(D) 54%

Ans: B

Volume of the block = (10 × 5 × 2) cm3 = 100 cm3

Volume of the cone carved out = $$({1}/{3} × {22}/{7} × 3 × 3 × 7)$$ cm3 = 66 cm3.

∴ Wood wasted = (100 – 66)% = 34%.

Question: 7

A 4 cm cube is cut into 1 cm cubes. The total surface area of all the small cubes is

(A) 96 cm2

(B) 384 cm2

(C) 424 cm2

(D) 824 cm2

Ans: B

Number of small cube formed = $$({4 × 4 × 4} / {1 × 1 × 1})$$ = 64.

Total surface area of the small cubes = [64 × (6 × 12] cm2 = 384 cm2.

Question: 8

The cost of the paint is Rs. 36.50 per kg. if 1 kg of paint covers 16 square feet, how much will it cost to paint outside of a cube having 8 feet each side?

(A) Rs. 692

(B) Rs. 768

(C) Rs. 866

(D) Rs. 876

Ans: D

Surface area of the cube = (6 × 82) sq.ft = 384 sq.ft.

Quantity of paint required = $$({384} / {16})$$ kg = 24 kg.

∴ Cost of painting = Rs. (36.50 × 24) = Rs. 876.

Question: 9

The dimensions of a cuboid are 7 cm, 11 cm and 13 cm. The total surface area is

(A) 311 cm2

(B) 411 cm2

(C) 622 cm2

(D) 722 cm2

Ans: C

Surface area = [2(7 × 11 + 11 × 13 + 7 × 13)] cm2

= (2 x 311) cm2 = 622 cm2.

Question: 10

The surface area of a cube is 150 cm2. Its volume is

(A) 64 cm3

(B) 94 cm3

(C) 125 cm3

(D) 135 cm3

Ans: C

6a2 = 150 ⇒ a2 = 25 ⇒ a = 5.

∴ Volume = a3 = 53 cm3 = 125 cm3.

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