How to center two lamps over a rectangular table

Say you have two lamps that you want to hang over a rectangular table. What should the distance be between them?

My intuition was to hang them at either a quarter of the length in from either side, with 1/2 the length of the table between them, the logic being that they’d then be centered over each their own half, thus giving roughly equal amounts of light to across the table.

Another attempt was to hang them 1/3rd in from each end, with another 1/3rd between them, the logic being that it’s equal distance.

As it turns out, the correct answer is neither. The correct answer is to hang it 3/10ths in from each end, with 4/10ths between them. So if your table is 2 meters or 200cm long, you would hang it with 60cm from edge to each lamp, and 80cm between the lamps (measuring from the center of the lamp, or the wire, not the rim). Similarly if your table, as ours, is 180cm, it’d be 56cm from each end, and 72cm between lamps.

How did I find this out? I asked my in-laws. Seriously, my mother-in-law recently got a pair of lamps hung over a rectangular table by a professional, and he used some formula, which she didn’t catch. So she offered to measure the distances. Her table was 2 meters. You get the picture.

This is all a matter of taste and subjectivity, of course, but we like the result.