Ask The Audience (Who Wants to be a Millionaire): Percentages Question

I am in the process of developing a Presentation Software of the game show Who Wants to be a Millionaire?, and I am trying to figure out how to calcuate the percentages of all four answers for the Ask The Audience lifeline (out of an audience of 100 people). If it were the first seven questions, I would give the right answer an overwhelming majority (80% or greater), but for the middle questions (Question #8 to Question #10 inclusive) I would give the right answer to a smaller majority (like 50 to 75 percent), and for the highest levels I would reduce the majority to 35 to 50 percent), and the remaining percentages to be calcuated from the remainder of the 100 in the virtual poll.

Is there any way to calculate the percentages of the answers based on the criteria I stated above?