GDP of a CountryThe gross domestic product (GDP) of a certain country is

f(t) = 0.1t³ + 0.4t² + 4t + 21 (0 t 4)

billion dollars in year t, where t is measured in years with t = 0 corresponding to 2010.

What was the GDP of the country in 2012? (In billions)

How fast was the GDP of the country changing in 2012? (In billion/yr)