Question 1:

The public health department of Smoke City reported 40 new cases of lung cancer in its population of 100,000 people between January 1, 2008 and December 31, 2009. What is the annual incidence of lung cancer for this population?

Question 2:

Four-hundred rats were injected with an experimental cancer treatment and followed for 6 months. Of the 400 rats, 81 died during the study period. Accrual of rat-time was as follows: 12 were followed for 1 month, 16 for 2 months, 18 for 3 months, 20 for 4 months, 15 for 5 months and 319 for the entire study period. What was the incidence density rate of mortality among the rats in this study, per 100 rat-months?