Question 908984
there are 75 contestants and 25 winning places, therefore in the first drawing you have 25/75 = 1/3, which means a one in three chance on the first draw
assuming you keep having drawings until all winning places have been determined
(1/3)+(24/74)+(23/73)+(22/72)+(21/71)+(20/70)+(19/69)+(18/68)+(17/67)+(16/66)+(15/65)+(14/64)+(13/63)+(12/62)+(11/61)+(10/60)+(9/59)+(8/59)+(7/58)+(6/57)+(5/57)+(4/56)+(3/55)+(2/54)+(1/53) = your probability of winning one of the winning places