Quantitative Aptitude Ques 1122
Question: A train travelling at 48 km/h crosses another train, having half its length and travelling in opposite directions at 42 km/h in 12 s. It also passes a railway platform in 46 s. The length of the railway platform is
Options:
A) 200 m
B) 300 m
C) 350 m
D) 400 m
Show Answer
Answer:
Correct Answer: D
Solution:
- Let the length of the train travelling at $ 48km/h $ be $ xm. $
Let the length of the platform be $ ym. $
Relative speed of train
$ =(48+42)km/h $
$ =90\times \frac{5}{18}m/s=25m/s $
Now, $ \frac{x+\frac{x}{2}}{25}=12 $
$ \Rightarrow $ $ \frac{3x}{50}=12 $
$ \Rightarrow $ $ 3x=12\times 50 $
$ \Rightarrow $ $ x=4\times 50=200m $ Again, $ \frac{200+y}{45}=48\times \frac{5}{18} $
$ \Rightarrow $ $ \frac{200+y}{45}=\frac{40}{3} $
$ \Rightarrow $ $ 600+3y=1800 $
$ \Rightarrow $ $ 3y=1200 $
$ \Rightarrow $ $ y=400 $
$ \therefore $ Length of railway platform $ =400m $
BETA
