A train takes 18 sec to cross a man who is standing on a platform . While it takes 30 sec to cross a 300 meter long platform . Find length of the train .
Answer & explanation
Correct answer: option 2
Let length of train = x meter
Time taken to cross a man is 18 sec . so total distance traveled is only length of train
Distance = Speed × Time
Speed = \(\frac{x}{18}\) ------ ( 1 )
Train takes 30 sec to cross a 300 meter long platform, total distance = 300 + x
Speed = \(\frac{300\;+\;x}{30}\) ---------- ( 2 )
Speed of train is same so put equation 1 equals to equation 2
\(\frac{x}{18}\) = \(\frac{300\;+\;x}{30}\)
30x = 5400 + 18x
12x = 5400 ⇒ x = 450 m
so, length of train = 450 m