21.  The areas of the three adjacent faces of a rectangular box which meet in a point are known. The product of these areas is equal to :

the volume of the box
twice the volume of the box
the square of the volume of the box
the cube root of the volume of the box

```Answer

Answer: Option  C Explanation:Let length = l, breadth = b and height = h, Then,
Product of areas of 3 adjacent faces = (lb * bh * lh) = (lbh)2 = (Volume)2. ```

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22.  The capacity of a tank of dimensions (8 m * 6 m * 2.5 m) is

120 litres
1200 litres`
12000 litres
120000 litres

```Answer

Answer: Option  D Explanation:Capacity of the bank = Volume of the tank
= (8*100*6*100*2.5*100 ⁄ 1000) litres = 120000 litres. ```

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23.  The edge of a cuboid are in the ratio 1 : 2 : 3 and its surface area is 88 cm2. The volume of the cuboid is :

24 cm3
48 cm3
64 cm3
120 cm3

```Answer

Answer: Option  B Explanation:Let the dimensions of the cuboid be x, 2x and 3x
Then, 2( x * 2x + 2x * 3x + x * 3x) = 88.
2x2 + 6x2 + 3x2 = 11x2 = 44
= x2 = 4
= x = 2.
Volume of the cuboid = (2 * 4 * 6) cm3 = 48 cm3
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24.  The height of a wall is six times its width and the length of the wall is seven times its height. If volume of the wall be 16128 cu. m, its width is :

4 m
4.5 m
5 m
6 m

```Answer

Answer: Option  A Explanation:Let the width of the wall be x metres.
Then, height = (6x) metres and length = (42x) metres.
= 42x * x * 6x = 16128
= x3 = (16128⁄42 * 6) = 64
= x = 4. ```

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25.  The maximum length of a pencil that can be kept in a rectangular box of dimensions 8 cm * 6 cm * 2 cm is :

2$\sqrt{\mathrm{13}}$ cm
2$\sqrt{\mathrm{14}}$ cm
2$\sqrt{\mathrm{26}}$ cm
10$\sqrt{2}$ cm

```Answer

Answer: Option  C Explanation:Required length = $\sqrt{\mathrm{82+ 62+ 22}}$ cm = $\sqrt{\mathrm{104}}$ cm = 2$\sqrt{\mathrm{26}}$ cm. ```

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