A train travelling with uniform speed crosses two bridges of lengths 300 m and 240 m in 21 s and 18 s, respectively. Find the speed of the train.


A) 72 km/h

B) 68 km/h

C) 65 km/h

D) 60 km/h

Correct Answer:
A) 72 km/h

Description for Correct answer:

Let length of the train = L

According to the question,

\( \Large \frac{L+300}{21} = \frac{L+240}{18} \)

=> \( \Large \frac{L+30}{7} = \frac{L+240}{6} \)

=> 6L + 1800 = 7L + 1680

Therefore, L = 120 m

Taking the length of the 2nd bridge into consideration,

Speed of train = \( \Large \frac{L+240}{18} = \frac{120+240}{18} m/s \)

= \( \Large \frac{360}{18} \times \frac{18}{5} km/h \)

= 72 km/h


Part of solved Trains questions and answers : >> Aptitude >> Trains








Comments

300m in 21 sec and 240m in 18 sec To cover 60m takes 3 sec 60/3=20m/sec 20*18/5=72km/h
- Shivam,Choudhary





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