A train running at $40 \frac{1}{2}$ km/h takes 24 seconds to cross a pole. How much time (in seconds) will it take to pass a 450 m long bridge ?

64

Distance = Speed  × Time

Speed = \(\frac{81}{2}\) km/h = \(\frac{81}{2}\)  × \(\frac{5}{18}\) = 11.25 m/sec

Length of train = 11.25 × 24 = 270 m

Now ,

Total distance = Length of train + length of bridge

= 270 + 450 = 720 m

Time taken = \(\frac{720}{11.25}\) = 64 sec