one out of three; every third person jeder Dritte {m} - https://www.dict.cc/?s=jeder+Dritte+
one out of three - um em cada três; um dos três - https://context.reverso.net/translation/english-portuguese/one+out+of+three
every third person jeder Dritte {m} - https://www.dict.cc/?s=jeder+Dritte+
every third - cada três; cada terceiro - https://context.reverso.net/translation/english-portuguese/every+third+person