At what time?

A plane flies from Athens to Brussels at maximum speed. Normally, flying at maximum speed would enable it to reach Brussels in four-fifths of the time that it takes to fly there at cruising speed. On this occasion, however, the velocity of a favorable wind enables it to get there in only half the time it would normally take at maximum speed. On the return journey, it leaves Brussels at 1 p.m. Ignoring time zones, and encountering the same velocity and direction of wind, at what time will the plane arrive back at Athens?

Click here for the solution

Never! Most of the information given is irrelevant. If the tails wind doubled its speed going, its velocity must have equaled that of the plane. On the way back, such a wind would effectively reduce the speed of the plane to zero.

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