1.) If the cumulative survival without dementia among a cohort of individuals is 81%, what is the cumulative incidence of dementia among this same cohort? Please show steps

2.) If a population was 20,598 on January 1, 2014 and 19,210 on December 31, 2014.During 2014, a total of 365 residents were HIV positive. What is the prevalence of HIV during 2014? please show steps

3.) If a population was 40,966 on July 1, 2010. During 2010, 26 residents were newly diagnosed with pancreatic cancer. What was the incidence of pancreatic cancer in 2010? please show steps