The formula with 4.7 substituted
miles = 4.7 ÷ 1.609344 = 2.920
The constant is an exact definition, not a rounded factor: the mile is 1.609344 km, the US gallon is 3.785411784 litres and the imperial gallon is 4.54609 litres. The Kilometres to Miles Converter explains where each comes from and gives a longer table.
At a walking pace of 5 km/h, 4.7 km takes about 56 minutes. At an easy running pace of 10 km/h it takes about 28. In metres it is 4,700.
What 4.7 kilometres means in practice
4.7 km is 2.92 miles, a whisker under three, which is why it is searched for: it is what a three mile route measures once the GPS trims the corners. Just under twelve laps of a track.