Populations - finite rate of increase - Biology help!?

[dongmin]

A biology student studied a population of house mice in a 5
acre vacant lot. In 1997, he determined that natality was 50 per year, mortality 30
per year, immigration 3 per year, and emigration was 13 per year.

2. In 2000, the population increased from 100 to 115 mice. How does the finite
rate of increase (lambda or ?) in 1997 compare with that in 2000? Show
calculations.

I'm not sure how to do this problem, can anyone help? Also for this problem:
6. 185 whooping cranes were counted in 2002 and a record population of 189
was counted in 2003. What was the finite rate of increase (?)?
a. -0.022 b. 0.978 c. 1.021 d. 2.659 e. 4

--Would the answer be C?

Thanks.
Thanks for your help, but do you know how to do problem #2 too in the beginning?

Thank you!