Running at a speed of 60 km per hour, a train passed through a 1-5 km long tunnel in two minutes. What is the length of the train ?

At 60 km/h the train covers 1 km per minute, so in 2 minutes it travels 2 km. When a train fully passes through a tunnel the distance its front travels from the moment it enters until its rear exits equals the tunnel length plus the train length. Thus: tunnel length + train length = distance travelled in 2 minutes. Substituting values: 1.5 km + train length = 2.0 km, so train length = 2.0 km − 1.5 km = 0.5 km = 500 m. Therefore the correct option is 500 m.