11.  Find the length of the longest rod that can be placed in a room 16 m long, 12 m broad and 1023 m high.

2213 m
2223 m
23 m
68 m

```Answer

Answer: Option  B Explanation:Required length = $\sqrt{\mathrm{\left(16\right)2+\left(12\right)2+ \left(32⁄3\right)2}}$ m.
= $\sqrt{\mathrm{256 + 144 +1024⁄9}}$ m
= $\sqrt{\mathrm{4624⁄9}}$ = 68⁄3 = 222⁄3. ```

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12.  Find the surface area of a 10 cm * 4 cm * 3 cm brick.

84 sq. cm
124 sq. cm
164 sq. cm
180 sq. cm

```Answer

Answer: Option  C Explanation:Surface area = [2 (10 * 4 + 4 * 3 + 10 * 3)] cm2 = (2 * 82) cm2 = 164 cm2. ```

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13.  Given that 1 cu. cm of marble weighs 25 gms, the weight of a marble block 28 cm in width and 5 cm thick is 112 kg. The length of the block is :

26.5 cm
32 cm
36 cm
37.5 cm

```Answer

Answer: Option  B Explanation:Let length = x cm. Then, x * 28 * 5 * 25⁄1000 = 112.
x = ( 112 * 1000⁄25 * 1⁄28 * 1⁄5 ) cm = 32 cm. ```

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14.  Half cubic metre of gold sheet is extended by hammering so as to cover an area of 1 hectare. The thickness of the sheet is :

0.0005 cm
0.005 cm
0.05 cm
0.5 cm

```Answer

Answer: Option  B Explanation:Volume of gold         = (1⁄2 * 100 * 100 * 100 ) cm3.
Area of Sheet          = 10000 m2 = (10000 * 100 * 100) cm2
Thickness of the sheet = (1 * 100 * 100 * 100⁄2 * 10000 * 100 * 100) cm= 0. 005 cm. ```

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15.  How many bricks, each measuring 25 cm * 11.25 cm * 6 cm, will be needed to build a wall 8 m * 6 m * 22.5 cm ?

5600
6000
6400
7200

```Answer

Answer: Option  C Explanation:Number of bricks = Volume of the wall⁄Volume of 1 brick = (800 * 600 * 225⁄25 * 1125 * 6) = 6400. ```

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