Subject: General Aptitude · Chapter: Problems on Trains · Exam: · Marks: · Difficulty:
A train crosses a signal post in x seconds. What is the length of the train? (NABARD, 2002) I. The train crosses a platform of 100 metres in y seconds. II. The train is running at the speed of 80 km / hr.
Answer
SELF-PRACTICE — the source book printed no answer.
Nothing is invented here, so this question has no answer on record.
Explanation
Let the length of the train be $l$ metres. Time taken to cross a signal post $=\frac{\text{Length of the train}}{\text{Speed of the train}} \Rightarrow x=\frac{l}{\text{Speed}}$. Time taken to cross the platform $=\frac{(l+100)}{\text{Speed}} \Rightarrow y=\frac{l+100}{\text{Speed}}$. Thus, from (i) and (ii), we can find $l$.
Explanation as extracted from the printed page; notation may be imperfect.