(2 marks) The average time between infection with the AIDS virus and developing AIDS has been estimated to be 8 years with a standard deviation of...

(2 marks) The average time between infection with the AIDS virus and developing AIDS has been estimated to be 8 years with a standard deviation of about 2 years. Approximately what fraction of the population develops AIDS within 4 years of infection? a) 6% b) 2.5% c) 3.25% d) 5.5% e) 1%