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?

Let the length of the train = L

Speed of the train = $$40\frac{1}{2}$$ km/h = $$\frac{81}{2}$$ km/h = $$\frac{81}{2}\times\frac{5}{18}$$ m/sec = $$\frac{45}{4}$$ m/sec

Train crosses a pole in 24 seconds.

$$\frac{L}{\frac{45}{4}}$$ = 24

$$\frac{4L}{45}$$ = 24

L = 270 m

Length of the train = L = 270 m

Time required for train to pass a 450 m long bridge = $$\frac{L+450}{\frac{45}{4}}$$

= $$\frac{270+450}{\frac{45}{4}}$$

= $$\frac{720\times4}{45}$$

= 64 sec

Hence, the correct answer is Option D