Belle was travelling in the MRT. She was seated at the last seat of the last coach.During the journey,she noted the time on her watch was 12.18 P.M when the train just entered an underground tunnel.The moment she exited from the tunnel,the time was 12.23 P.M.Given that the train travelled at an average speed of 18 km/h and that the tunnel is 1350m long,find the length of the train in metres.