Quantitative Aptitude - Arithmetic Ability Questions

Q:

A train travelling at 48 kmph crosses another train, having half its length and travelling in opposite direction at 42 kmph, in 12 sec. It also covers a bridge in 45 sec. Find the length of the bridge ?

A) 250 mts B) 400 mts
C) 320 mts D) 390 mts
 
Answer & Explanation Answer: B) 400 mts

Explanation:

Let the length of the 1st train = L mts

Speed of 1st train = 48 kmph

Now the length of the 2nd train = L/2 mts

Speed of 2nd train = 42 kmph

Let the length of the bridge = D mts

Distance = L + L/2 = 3L/2

Relative speed = 48 + 42 = 90 kmph = 90 x 5/18 = 25 m/s(opposite)

Time = 12 sec

=> 3L/2x25 = 12

=> L = 200 mts

Now it covers the bridge in 45 sec

=> distance = D + 200

Time = 45 sec

Speed = 48 x5/18 = 40/3 m/s

=> D + 200/(40/3) = 45

=> D = 600 - 200 = 400 mts

Hence, the length of the bridge = 400 mts.

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Filed Under: Problems on Trains
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15 5873
Q:

If A = log321875 and B = log2432187, then which one of the following is correct?

A) A B) A=B
C) A>B D) can't be determined
 
Answer & Explanation Answer: B) A=B

Explanation:

 Given A = log321875 and B = log2432187

B = log352187 = log321875

=> A

Therefore, A = B

   

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Filed Under: Logarithms
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7 5870
Q:

Find the number of ways to take 20 objects and arrange them in groups of 5 at a time where order does not matter.?

A) 57090 B) 15540
C) 15504 D) 23670
 
Answer & Explanation Answer: C) 15504

Explanation:

C520 = 15504

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0 5869
Q:

The length, breadth and height of a room are in the ratio 7:3:1. If the breadth and height are doubled while the length is halved, then by what percent the total area of the 4 walls of the room will be increased  ?

A) 90% B) 88%
C) 85% D) 84%
 
Answer & Explanation Answer: A) 90%

Explanation:

Let length, breadth and height of the room be 7, 3, 1 unit respectively.

Area of walls = 2(l+b)xh = 2(7+3)x1 = 20 sq. unit.

Now, length, breadth and height of room will become 3.5, 6 and 2 respectively. 

Area of walls = 2(l+b)xh = 2(3.5+6)x2 = 38 sq. unit. 

% Increase in the area of walls = (38-20)x100/20 = 90%.

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Filed Under: Area
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15 5865
Q:

Three different containers contain 1365 litres, 1560 litres and 1755 litres of mixtures of milk and water respectively. What biggest measure that can measure all the different quantities exactly ?

A) 37 lit B) 97 lit
C) 129 lit D) 195 lit
 
Answer & Explanation Answer: D) 195 lit

Explanation:

From the given data,

containers contain mixtures of milk and water as 1365 lit, 1560 lit and 1755 lit.

 

Biggest measure that can measure all these different quantities exactly can be given by

HCF of (1365, 1560, 1755) 

That can be found as 

 

HCF of 1365, 1755 = 195

Now, HCF of 195 and 1560 = 195

 

Hence, biggest measure that can measure all the given different quantities exactly is 195 lit.

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Filed Under: HCF and LCM
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11 5852
Q:

A boat can move 5 km/hr in still water. If the river is running at 1 km/hr, it takes it 75 min to move to a place and back. How far is the place?

A) 3 kms B) 5 kms
C) 6 kms D) 4 kms
 
Answer & Explanation Answer: A) 3 kms

Explanation:

Let the place be at a distance of 'd' kms

From the given data,

d5 - 1 + d5 + 1 = 7560 kmsd4 + d6 = 54

5d/12 = 5/4 => d = 3 kms.

 

Hence, the place is 3 kms far.

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Filed Under: Boats and Streams
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21 5848
Q:

If 16 men working 7 hours day can plough a fieid in 4l days, inhow many days will 14 men working 12 hours a clay plough the samefield ?

A) 46 B) 32
C) 35 D) 30
 
Answer & Explanation Answer: B) 32

Explanation:

(Men 14 : 16) : (Hrs/Day 12 : 7) :: 48 : x
14 * 12 * x = 16 * 7 * 48 or x = 32

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Filed Under: Chain Rule

11 5848
Q:

The average of ages of threee persons is 60 years . Those ages are in the proportion of 1:2:3. what is the age of the youngest one among them?

Answer

Suppose the ages of three persons are x, 2x, 3x years respectively 





Hence, age of youngest person = x = 30 years.

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Subject: Problems on Ages

3 5840