As general rule, the strong beat in Latin music is at beat 1. But in the CD "Rhythm of Results" of Ton Greten (http://www.dsi-london.com/site/?action=prod_page&pid=9163&cat_id=13&type=18&sub_id) he said that the strong beat in Rumba is in beat 4 (it is syncopated!!!). I also do not know why Walter Laid said in his book that Rumba has beat 4 strong)

Therefore what is the exact music of International Rumba (used in WDC and WDSF contests)? Rumba with strong beat in beat 1 or Rumba with strong beat in beat 4? If they use beat 4 strong, what is the reason?

Can anyone know it clearly? And how about music rhythm of Chacha in WDC & WDSF?