The length of a bridge which a 130 metres long train travelling at 45 Km/hr can cross in 30 seconds is __________

245 m

Speed in m/s=45×  \(\frac{5 }{ 18}\)m/sec =  \(\frac{25 }{ 2}\) m/sec

Time = 30 sec.

Let the length of bridge be x metres.

Then  \(\frac{\text{130 + x}}{ 30}\)= \(\frac{25 }{ 2}\)

⇒2(130+x)=750

⇒ 260 + 2x = 750

⇒ 2x = 490

⇒x=245m