Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 3)
3.
The length of the bridge, which a train 130 metres long and travelling at 45 km/hr can cross in 30 seconds, is:
Answer: Option
Explanation:
| Speed = |  |
45 x | 5 |  m/sec |
= | |
25 | m/sec. |
| 18 | 2 |
Time = 30 sec.
Let the length of bridge be x metres.
| Then, | 130 + x | = | 25 |
| 30 | 2 |
2(130 + x) = 750
x = 245 m.
Video Explanation: https://youtu.be/M_d8WufJWKc
Discussion:
247 comments Page 15 of 25.
Suren said:
1 decade ago
@Sai.
Your method is fantastic and very easy to understand. Great job! keep it up man. Thanks!
Your method is fantastic and very easy to understand. Great job! keep it up man. Thanks!
SK Lodhi said:
1 decade ago
130+B = 30 Sec.*45*5/18 m/s(time*speed).
130+B = 375 m.
Where B = length of the Bridge = 375 - 130 = 245 meters.
130+B = 375 m.
Where B = length of the Bridge = 375 - 130 = 245 meters.
Radha said:
1 decade ago
Please explain method clearly how we will dot 750?
Safina M said:
1 decade ago
Hey Radha,
Cross multiply (139+x)/30=25/2 i.e,
2*(130+x)=30*25.
i.e., 260+2x=750.
2x=750-260.
2x=490.
x=490/2.
Hence, x=245.
Cross multiply (139+x)/30=25/2 i.e,
2*(130+x)=30*25.
i.e., 260+2x=750.
2x=750-260.
2x=490.
x=490/2.
Hence, x=245.
Varalakshmi saravanan said:
1 decade ago
Hi Friends it's very simple.
Length of the Train = 130 m.
Speed = 45 km/hr after converting into m/s we will get (45*5/18) => 25/2.
Time = 30 sec.
Length of bridge = x + length of train.
X+length of train = Speed of the train*time.
X+130 = 25/2*30.
X+130 = 375.
X = 375-130.
X = 245.
Length of the Train = 130 m.
Speed = 45 km/hr after converting into m/s we will get (45*5/18) => 25/2.
Time = 30 sec.
Length of bridge = x + length of train.
X+length of train = Speed of the train*time.
X+130 = 25/2*30.
X+130 = 375.
X = 375-130.
X = 245.
Deep said:
1 decade ago
Easy method is by using time and distance formula.
Bala said:
1 decade ago
45*5/18 = 12.5.
12.5*30 = 375.
375-130 = 245.
12.5*30 = 375.
375-130 = 245.
Madan said:
1 decade ago
45*5/18 = 12.5.
12.5*30 = 375.
375-130 = 245.
12.5*30 = 375.
375-130 = 245.
Anusha said:
1 decade ago
Hi friends I did in a different way:
Let the length of train b = 130.
Let the length of bridge b = x.
Therefore distance = x + 130.
Time = 30 sec.
S = 45 km/h = 45*5/18 = 25/2 m/s.
So, in this case distance = 375 m.
So, d = x + 130 substituting the value of d (distance).
We get 375 - 130 = x.
X = 245 m.
Let the length of train b = 130.
Let the length of bridge b = x.
Therefore distance = x + 130.
Time = 30 sec.
S = 45 km/h = 45*5/18 = 25/2 m/s.
So, in this case distance = 375 m.
So, d = x + 130 substituting the value of d (distance).
We get 375 - 130 = x.
X = 245 m.
Shashi said:
1 decade ago
We can solve by using formula also @Anusha.
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