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Q:

A right triangle with sides 3 cm, 4 cm and 5 cm is rotated the side of 3 cm to form a cone. The volume of the cone so formed is:

A) 12 pi cub.cm B) 15 pi cub.cm
C) 16 pi cub.cm D) 20 pi cub.cm
 
Answer & Explanation Answer: A) 12 pi cub.cm

Explanation:

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Q:

A metallic sheet is of rectangular shape with dimensions 48 m x 36 m. From each of its corners, a square is cut off so as to make an open box. If the length of the square is 8m, the volume of the box (in m3) is:

A) 4830 B) 5120
C) 6420 D) 8960
 
Answer & Explanation Answer: B) 5120

Explanation:

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Q:

A boat having a length 3 m and breadth 2 m is floating on a lake. The boat sinks by 1cm when a man gets on it. The mass of the man is:

A) 12 kg B) 60 kg
C) 72 kg D) 96 kg
 
Answer & Explanation Answer: B) 60 kg

Explanation:

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Q:

A hall is 15 m long and 12 m broad. If the sum of the areas of the floor and the ceiling is equal to the sum of the areas of four walls, the volume of the hall is:

A) 720 B) 900
C) 1200 D) 1800
 
Answer & Explanation Answer: C) 1200

Explanation:

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Q:

A rectangular field is to be fenced on three sides leaving a side of 20 feet uncovered. If the area of the field is 680 sq. feet, how many feet of fencing will be required?

A) 34 B) 40
C) 68 D) 88
 
Answer & Explanation Answer: D) 88

Explanation:

We have: l = 20 ft and lb = 680 sq. ft.

So, b = 34 ft.

Length of fencing = (l + 2b) = (20 + 68) ft = 88 ft.

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Q:

The length of a rectangle is halved, while its breadth is tripled. What is the percentage change in area?

A) 25% increase B) 50% increase
C) 50% decrease D) 75% decrease
 
Answer & Explanation Answer: B) 50% increase

Explanation:

Let original length = x and original breadth = y.

Original area = xy.

 

New length = x/2 and New breadth = 3y.

New area = (x/2 * 3y) = (3/2 )xy

 

Therefore,  Increase % = [(1/2)xy * (1/xy) * 100] % = 50%

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Q:

What is the least number of squares tiles required to pave the floor of a room 15 m 17 cm long and 9 m 2 cm broad?

A) 814 B) 820
C) 840 D) 844
 
Answer & Explanation Answer: A) 814

Explanation:

Length of largest tile = H.C.F. of 1517 cm and 902 cm = 41 cm. 

Area of each tile = (41 x 41) sq.cm 

Required number of tiles = 1517 x (902/41) x 41 = 814

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Q:

A towel, when bleached, was found to have lost 20% of its length and 10% of its breadth. The percentage of decrease in area is:

A) 10% B) 10.08%
C) 20% D) 28%
 
Answer & Explanation Answer: D) 28%

Explanation:

Let original length = x and original breadth = y. 

 

Decrease in area = xy -[(80/100x) * (90/100y)]  

=[(xy-(18/25)xy)]

=(7/25)xy

Decrease % =[(7/25)xy * (1/xy) * 100] =28%

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