1.  If the area of the base of a right circular cone is 3850 cm2 and its height is 84 cm, then the curved surface area of the cone is :

10001 cm2
10010 cm2
10100 cm2
11000 cm2

```Answer

Answer: Option  B Explanation:πr2 = 3850.
r2 = (3850 * 7⁄22) = 1225.
r = 35.
Now, r = 35 cm, h = 84 cm.
So, l =$\sqrt{\mathrm{\left(35\right)2}}$ + $\sqrt{\mathrm{\left(84\right)2}}$ = $\sqrt{\mathrm{1225 + 7056}}$ = $\sqrt{\mathrm{8281}}$ = 91 cm.
Curved surface area = (22⁄7 * 35 * 91) cm2 = 10010 cm2. ```

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2.  The sum of the radius of the base and the height of a solid cylinder is 37 metres. If the total surface area of the cylinder be 1628 sq. metres, its volume is :

3180 m3
4620 m3
5240 m3
None of these

```Answer

Answer: Option  B Explanation:(h + r) = 37 and 2πr(h + r) = 1628.
2πr * 37 = 1628 or r = (1628⁄2 * 37 * 7⁄22) = 7.
So, r = 7 m and h = 30 m.
Volume = (22⁄7 * 7 * 7 * 30) m3 = 4620 m3. ```

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3.  The volume of a right circular cylinder whose curved surface area is 2640 cm2 and circumference of its base is 66 cm, is :

3465 cm2
7720 cm2
13860 cm2
55440 cm2

```Answer

Answer: Option  C Explanation:2πr = 66;
r = (66 * 1⁄2 * 7⁄22) = 21⁄2 cm.
2πrh⁄2πr = (2640⁄66).
h = 40 cm.
Volume = (22⁄7 * 21⁄2 * 21⁄2 * 40) cm3 = 13860 cm3. ```

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4.  The surface area of a cube is 600 cm2. The length of its diagonal is :

10$\sqrt{3}$
10$\sqrt{2}$
10$\sqrt{2}$
10$\sqrt{3}$

```Answer

Answer: Option  D Explanation:6a2 = 600.
a2 = 100 .
a = 10.
Diagonal =$\sqrt{3}$a = 10$\sqrt{3}$ cm. ```

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5.  The curved surface area of a cylindrical pillar is 264 m2 and its volume is 924 m3. Find the ratio of its diameter to its height,

3 : 7
7 : 3
6 : 7
7 : 6

```Answer

Answer: Option  B Explanation:πr2h⁄2πrh = 924⁄264.
r = (924⁄264 * 2 ) = 7 m.
And, 2πrh = 264.
h = (264 * 7⁄22 * 1⁄2 * 1⁄7) = 6 m.
Required ratio = 2π⁄h = 14⁄6 = 7 : 3. ```

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