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1.  A cube of edge 5 cm is cut into cubes each of edge 1 cm. The ratio of the total surface area of one of the small cubes to that of the large cube is equal to :


1 : 5
1 : 25
1 : 125
1 : 625


Answer

 Option

Required ratio = 6 * 1 * 1⁄6 * 5 * 5 = 1⁄25 = 1 : 25.

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2.  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

 Option

πr2 = 3850.
r2 = (3850 * 7⁄22) = 1225.
   r = 35.
Now, r = 35 cm, h = 84 cm.
So, l =(35)2 + (84)2 = 1225 + 7056 = 8281 = 91 cm.
Curved surface area = (22⁄7 * 35 * 91) cm2 = 10010 cm2.

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


10⁄3
10⁄2
102
103


Answer

 Option

6a2 = 600.
 a2 = 100 .
  a = 10.
Diagonal =3a = 103 cm.

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4.  The curved surface of a right circular cone of height 15 cm and base diameter 16 cm is :


60π cm2
68π cm2
120π cm2
136π cm2


Answer

 Option

h = 15 cm, r = 8 cm. So, l = r2 + h2 = 82 + (15)2 = 17 cm.
Curved surface area = πrl = (π * 8 * 17) cm2 = 136π cm2.

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5.  The volume of a sphere is 4851 cu. cm. Its curved surface area is :


1386 cm2
1625 cm2
1716 cm2
3087 cm2


Answer

 Option

4⁄3 * 22⁄7 * R2.
 R3 = (4851 * 3⁄4 * 7⁄22) = (21⁄2)3.
  R = 21⁄2.
Curved surface area = (4 * 22⁄7 * 21⁄2 * 21⁄2) cm2 = 1386 cm2.

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