1.
Two cubes, each of side 12 cm, are joined end to end. The surface area of the resulting cuboid is
- A.1240 sq cm
- C.2250 sq cm
- B.1440 sq cm
- D.4252 sq cm
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| 4 (24 x 12) + 2 (12 x 12) = 1440 sq cm. |
2.
A large cube is formed from the material obtained by melting three smaller cubes of 3, 4 and 5 cms side, What is the ratio of the total surface areas of the smaller cubes and the large cube?
- A.2 : 1
- C.25 : 18
- B.3 : 2
- D.27 : 20
- Answer & Explanation
- Report
Answer : [C]
Explanation :
Explanation :
| Sum of the surface areas of three smaller cubes = 6 x 32 + 6 x 42 + 6 x 52 = 300 cm2 | ||||||
| Volume of large cube = 33 + 43 + 53 = 216 cm3 | ||||||
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| Total S.A. of smaller cubes: S.A. of large cube = 300 : 216 = 25 : 18. | ||||||
3.
| Three cubes of metal whose edges are in the ratio 3 : 4 : 5 are melted into a single cube, the | |||||||
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- A.24 m, 32 m, 40 m
- C.30 m, 22 m, 18 m
- B.40 m, 32 m, 24 m
- D.48 m, 36 m, 24 m
- Answer & Explanation
- Report
Answer : [A]
Explanation :
Explanation :
| Since the edges of the cubes are in the ratio 3 : 4 : 5, let these be 3k, 4k, 5k metres. respectively. | ||||||||
| Their volumes are 27 k3, 64 k3, 125 k3 cu m. | ||||||||
| Thus, the volume of the single cube = (27 + 64 + 125) k3 cu m. | ||||||||
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| Therefore, the length of the edges of three cubes are 3 x 8, 4 x 8, 5 x 8 m, that is 24 m, 32 m, 40 m. | ||||||||
4.
The weight of the solid cube of iron of 1 cm edge is 17 gm. What should be the weight of a similar cube of edge 3 cm?
- A.449 gm
- C.469 gm
- B.459 gm
- D.4390 gm
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| When edge is increased 3 times, the volume or weight is increased 33, i.e. 27 times | ||||||
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5.
A cubical metallic tank whose each edge measures 30 cm, is completely filled with water. If 2, 7 litres water is taken out of it, what will be the depth of remaining water in tank?
- A.37 cm
- C.17 cm
- B.27 cm
- D.None of these
- Answer & Explanation
- Report
Answer : [B]
Explanation :
Explanation :
| Volume of the cubical metallic tank = l x b x h | ||||||||||||
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