Quantitative Aptitude

General Questions

Quantitative Aptitude Exercise Mode

General Questions

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Question 11
Two goods train each 500 m long, are running in opposite directions on parallel tracks. Their speeds are 45 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one.

A
12 sec
B
24 sec
C
48 sec
D
60 sec
Correct Answer: Option B

Relative speed = = (45 + 30) km/hr
= ( 75 x 5 ( m/sec
18
= ( 125 ( m/sec.
6

We have to find the time taken by the slower train to pass the DRIVER of the faster train and not the complete train.

So, distance covered = Length of the slower train.

Therefore, Distance covered = 500 m.

Therefore Required time = ( 500 x 6 ( = 24 sec.
125

Question 12
Two trains of equal lengths take 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train be 120 metres, in what time (in seconds) will they cross each other travelling in opposite direction?

A
10
B
12
C
15
D
20
Correct Answer: Option B

Speed of the first train = ( 120 ( m/sec = 12 m/sec.
10

Speed of the second train = ( 120 ( m/sec = 8 m/sec.
15

Relative speed = (12 + 8) = 20 m/sec.

Therefore Required time = [ (120 + 120) ] sec = 12 sec.
20

Question 13
A train 108 m long moving at a speed of 50 km/hr crosses a train 112 m long coming from opposite direction in 6 seconds. The speed of the second train is:

A
48 km/hr
B
54 km/hr
C
66 km/hr
D
82 km/hr
Correct Answer: Option D

Let the speed of the second train be x km/hr.

Relative speed = (x + 50) km/hr
= [ (x + 50) x 5 ] m/sec
18
= [ 250 + 5x ] m/sec.
18

Distance covered = (108 + 112) = 220 m.

Therefore 220 = 6
( 250 + 5x (
18

=> 250 + 5x = 660

=> x = 82 km/hr.

Question 14
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?

A
23 m
B
23.22 m
C
27.77 m
D
29 m
Correct Answer: Option C

Relative speed = (40 - 20) km/hr

= ( 20 x 5 ( m/sec = ( 50 ( m/sec.
18 9

ThereforeLength of faster train

= ( 50 x 5 ( m = 250 m = 27 7 m.
9 9 9

Question 15
A train overtakes two persons walking along a railway track. The first one walks at 4.5 km/hr. The other one walks at 5.4 km/hr. The train needs 8.4 and 8.5 seconds respectively to overtake them. What is the speed of the train if both the persons are walking in the same direction as the train?

A
72 km/hr
B
66 km/hr
C
81 km/hr
D
78 km/hr
Correct Answer: Option C

4.5 km/hr :

= ( 4.5 x 5 ( m/sec = 5 m/sec = 1.25 m/sec, and
18 4

5.4 km/hr :

= ( 5.4 x 5 ( m/sec = 3 m/sec = 1.5 m/sec.
18 2

Let the speed of the train be x m/sec.

Then, (x - 1.25) x 8.4 = (x - 1.5) x 8.5

=> 8.4x - 10.5 = 8.5x - 12.75

=> 0.1x = 2.25

=> x = 22.5

Therefore Speed of the train :

= ( 22.5 x 18 ( km/hr = 81 km/hr.
5

Question 16
A train overtakes two persons who are walking in the same direction in which the train is going, at the rate of 2 kmph and 4 kmph and passes them completely in 9 and 10 seconds respectively. The length of the train is:

A
72 m
B
54 m
C
50 m
D
45 m
Correct Answer: Option C

2 kmph = ( 2 x 5 ( m/sec = 5 m/sec.
18 9

4 kmph = ( 4 x 5 ( m/sec = 10 m/sec.
18 9

Let the length of the train be x metres and its speed by y m/sec.

Then, ( x ( = 9 and ( x ( = 10.
y - 5
9
y - 10
9

Therefore 9y - 5 = x and 10(9y - 10) = 9x

=> 9y - x = 5 and 90y - 9x = 100.

On solving, we get: x = 50.

Therefore Length of the train is 50 m.

Question 17
Two stations A and B are 110 km apart on a straight line. One train starts from A at 7 a.m. and travels towards B at 20 kmph. Another train starts from B at 8 a.m. and travels towards A at a speed of 25 kmph. At what time will they meet?

A
9 a.m.
B
10 a.m.
C
10.30 a.m.
D
11 a.m.
Correct Answer: Option B

Suppose they meet x hours after 7 a.m.

Distance covered by A in x hours = 20x km.

Distance covered by B in (x - 1) hours = 25(x - 1) km.

Therefore 20x + 25(x - 1) = 110

=> 45x = 135

=> x = 3.

So, they meet at 10 a.m.

Question 18
A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is 

A
400 m
B
450 m
C
560 m
D
600 m
Correct Answer: Option A

Let the length of the first train be x metres.

Then, the length of the second train is ( x ( metres.
2

Relative speed:

= (48 + 42) kmph = ( 90 x 5 ( m/sec = 25 m/sec.
18

Therefore [x + (x/2)] = 12 or 3x = 300     or     x = 200.
25 2

Therefore Length of first train = 200 m.

Let the length of platform be y metres.

Speed of the first train :

= ( 48 x 5 ( m/sec = 40 m/sec.
18 3

Therefore (200 + y) x 3 = 45
40

=> 600 + 3y = 1800

=> y = 400 m.

Question 19
Two, trains, one from Howrah to Patna and the other from Patna to Howrah, start simultaneously. After they meet, the trains reach their destinations after 9 hours and 16 hours respectively. The ratio of their speeds is:

A
2 : 3
B
4 : 3
C
6 : 7
D
9 : 16
Correct Answer: Option B

Let us name the trains as A and B. Then,

(A's speed) : (B's speed) = b : a = 16 : 9 = 4 : 3.

Question 20
A 270 metres long train running at the speed of 120 kmph crosses another train running in opposite direction at the speed of 80 kmph in 9 seconds. What is the length of the other train?

A
230 m
B
240 m
C
260 m
D
320 m
E
None of these
Correct Answer: Option A

Relative speed = (120 + 80) km/hr

   = 200 x 5 m/sec
18

   = 500 m/sec.
9

Let the length of the other train be x metres.

Then, x + 270 = 500
9 9

x + 270 = 500

x = 230.