Step 1 :The population model for Alphaville is \(P(t)=45t+5000\).
Step 2 :The population model for Betaburgh is \(Q(t)=2550e^{.04t}+950\).
Step 3 :We substitute \(t=10\) (since 2000 is 10 years after 1990) into the population models to find the populations.
Step 4 :The population of Alphaville in 2000 is \(P_{2000} = 5450\) people.
Step 5 :The population of Betaburgh in 2000 is \(Q_{2000} = 4754.152978985239\) people.
Step 6 :We round these numbers to the nearest hundred.
Step 7 :The rounded population of Alphaville in 2000 is \(P_{2000_{rounded}} = 5400\) people.
Step 8 :The rounded population of Betaburgh in 2000 is \(Q_{2000_{rounded}} = 4800\) people.
Step 9 :Final Answer: The population of Alphaville in 2000 was approximately \(\boxed{5400}\) people and the population of Betaburgh in 2000 was approximately \(\boxed{4800}\) people.