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A long train, half a kilometre long, is about to enter a long tunnel.

The tunnel is 10k long.

If the speed of the train is 35kph, how long will it take for the entire train to pass through the tunnel - from the front of the train entering to the end of the train leaving the tunnel?

[Ref: ZRWF]

Answer: The train takes 18 minutes.

The front of the train has to initially travel 10k to leave the tunnel, and then a further 0.5k until the rear of the train has also left the tunnel - a total of 10.5k.

The train is travelling at 35kph and using Time = Distance ÷ Speed gives:

Time = 10.5 ÷ 35 = 0.3 hours.

Convert this to minutes:

0.3 x 60 = 18 minutes. QED.

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