A train leaves Paris for Marseille at 230 km/h (ignore acceleration); at the same time a train leaves Marseille for Paris at 210 km/h; if the cities are 660 km apart, how long will it take the trains to meet?
Un train quitte Paris pour Marseille à 230 km/h (ignorer l’accélération); en même temps un train quitte Marseille pour Paris à 210 km/h; si les villes sont à 660 km l'une de l'autre, dans combien de temps les trains se croisent-ils?
Sacre Bleu Mr Quiz - you are getting more devious!!
As the trains are travelling at different speeds the Paris / Marseille train will have travelled 345 km and the Marseille / Paris train will have travelled 315 km when they meet. Now this is where you are Devious Mr. Quiz! The faster train from Paris will take 1.642 hours to get to the meeting point ( 98.568, say 99 minutes) but the slower train from Marseille will take 1.5 hours (90 minutes). So the slower train gets there first!
In 1 hour they will have reduced their distance from (230+210=) 440 kms, just two thirds of 660 km. Another half hour to cover the last 220 km and there they are. So 1h30 is the time it will take for the trains to meet.
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