How are the number of laps in an F1 race determined?

Question

The number of laps in a F1 race seem to differ wildly. Obviously the length of each lap varies from circuit to circuit, but how are the number of laps for each race decided?

Additionally, is this number chosen by the owners of the race track, or something decided by the FIA/ teams?

Answer 1

The number of laps are decided by taking a distance of 305 km and dividing it by the length of a lap (rounded up), which varies from racetrack to racetrack. ₍₁₎

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quoting the official regulations (from 2011):

5.3
The distance of all races, from the start signal referred to in Article 38.9 to the chequered flag, shall be equal to the least number of complete laps which exceed a distance of 305 km (Monaco 260km). However, should two hours elapse before the scheduled race distance is completed, the leader will be shown the chequered flag when he crosses the control line (the Line) at the end of the lap during which the two hour period ended. However, should the race be suspended (see Article 41) the length of the suspension will be added to this period.