At what minimum distance from the sign will a slippery section of road begin in a populated area?

Explanation

Warning sign 1.15 "Slippery road" stands 50-100 m before the dangerous section in built-up areas and 150-300 m outside them. Another distance would be shown on plate 8.1.1, and there is none here, so the slippery section starts at least 50 m after the sign (Rules, sign 1.15).