Practice Crossing bridge platform - quantitative aptitude Online Quiz (set-1) For All Competitive Exams
Q-1) A moving train passes a platform 50 metre long in 14 seconds and a lamp post in 10 seconds. The speed of the train (in km/h) is :
(a)
(b)
(c)
(d)
Let the length of train be x metre.
When a train crosses a platform, distance covered by it
= length of train and platform.
Speed of train
= ${x + 50}/14 = x/10$
${x + 50}/7 = x/5$
7x = 5x + 250
7x - 5x = 250
2x = 250 ⇒ x = $250/2$ = 125 metre
Speed of train = $x/10$
= $(125/10)$ m./sec.
= $(125/10 × 18/5)$ kmph = 45 kmph.
Q-2) A train 50 metres long passes a platform of length 100 metres in 10 seconds. The speed of the train in metre/second is
(a)
(b)
(c)
(d)
Using Rule 10,If a train of length x m crosses a platform/tunnel/bridge of length y m with the speed u m/s in t seconds, then,t = ${x + y}/u$
Speed of train
= $\text"Length of (train + platform)"/ \text"Time taken in crossing"$
= ${(50 + 100)}/10 = 150/10$ = 15 m/sec
Q-3) A train 50 metre long passes a platform 100 metre long in 10 seconds. The speed of the train in km/hr is
(a)
(b)
(c)
(d)
Using Rule 10,
Speed of train
= $\text"Length of platform and train"/ \text"Time taken incrossing"$
= $({100 + 50}/10)$ metre/second
= 15 metre/second
= $(15 × 18/5)$ kmph = 54 kmph
Q-4) A train, 200 metre long, is running at a speed of 54 km/hr. The time in seconds that will be taken by train to cross a 175 metre long bridge is :
(a)
(b)
(c)
(d)
Speed of train = 54 kmph
= $({54 × 5}/18)$ m/sec.
= 15 m/sec.
Required time
= $\text"Length of train and bridge"/ \text" Speed of train"$
= $({200 + 175}/15)$ seconds
= $(375/15)$ seconds = 25 seconds
Q-5) A train takes 18 seconds to pass through a platform 162 m long and 15 seconds to pass through another platform 120 m long. The length of the train (in m) is :
(a)
(b)
(c)
(d)
Using Rule 10,
Let the length of the train be x metres.
When a train corsses a platform it covers a distance equal to the sum of lengths of train and platform.
Also, the speed of train is same.
${x + 162}/18 = {x + 120}/15$
6x + 720 = 5x + 810
6x - 5x = 810 - 720
x = 90
The length of the train = 90m.
Q-6) A train 800 metres long is running at the speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in metres) is :
(a)
(b)
(c)
(d)
When a train crosses a tunnel, it covers a distance equal to the sum of its own length and tunnel.
Let the length of tunnel be x Speed = 78 kmph
= ${78 × 1000}/{60 × 60}$ m/sec. = $65/3$ m/sec.
Speed = $\text"Distance"/\text"Time"$
$65/3 = {800 + x}/60$
(800 + x ) × 3 = 65× 60
800 + x = 65 × 20 m
x = 1300 - 800 = 500
Length of tunnel = 500 metres.
Using Rule 10,
Here, x = 800 m, u = 78 km/hr
= 78$5/18 = 65/3$ m/sec
t = 1 min = 60 sec, y = ?
using t = ${x + y}/u$
$60 = {800 + y}/{65/3}$
60 × $65/3$ = 800 + y
1300 - 800 = y ⇒ y = 500 metres
Q-7) A train 150 metre long takes 20 seconds to cross a platform 450 metre long. The speed of the train in, km per hour, is :
(a)
(b)
(c)
(d)
Speed of train
= $\text"length of platform and train"/ \text"Time taken in crossing"$
=$({450 +150}/20)$ m/sec.
= $(600/20)$ m/sec.
= $(30 × 18/5)$ kmph = 108 kmph.
Q-8) A train travelling at a speed of 30 m/sec crosses a platform, 600 metres long, in 30 seconds. The length (in metres) of train is
(a)
(b)
(c)
(d)
Using Rule 10,
Let the length of train be x
According to the question,
${x + 600}/30$ = 30
x + 600 = 900
x = 900 - 600 = 300 m
Q-9) The length of a train and that of a platform are equal. If with a speed of 90 km/hr the train crosses the platform in one minute, then the length of the train (in metres) is :
(a)
(b)
(c)
(d)
Using Rule 1,If a train crosses an electric pole, a sitting/standing man, km or mile stone etc. then distance = Length of train. Then,Length of train = Speed × TimeAnd Time = $\text"Length of train"/\text"Speed"$ andSpeed = $\text"Length of train"/\text"Time"$
Let the length of train be x metre Speed = 90 km/hr
= ${90 × 5}/18$ metre /sec. = 25 metre/sec.
Distance covered in 60 sec.
= 25 × 60 = 1500 metres
Now, according to question,
2x = 1500 ⇒ x = 750 metre
Q-10) The lengths of a train and that of a platform are equal. If with a speed of 90 km/hr the train crosses the platform in one minute, then the length of the train (in metres) is
(a)
(b)
(c)
(d)
Let, length of train = length of platform = x metre
Speed of train = 90 kmph
= $({90 × 5}/18)$ m/sec.
= 25 m/sec.
Speed of train
= $\text"Length of train and platform"/ \text"Time taken in crossing"$
25 = ${2x}/60$
2x = 25 × 60
$x = {25 × 60}/2$ = 750 metre