a)
so, if the population doubled in 5 years, that means t = 5. So say, if we use an amount for "i" or P in your case, to be 1, then after 5 years it'd be 2, and thus i = 1 and A = 2, let's find "r" or "k" in your equation.
b)
A = 10,000, t = 3
Step-by-step explanation:
when the scale says 1:500000, then that means 1 unit in the map corresponds to 500000 units in reality.
and so, 3.2 cm on the map are
3.2 × 500000 cm in reality.
3.2 × 500000 = 1,600,000 cm = 16,000 m = 16 km