Create and solve exponential equation

A population of mice quadruples every 6 months. If a mouse nest started out with 2 mice, how many mice would there be after 2 years?

Write an equation and then use it to solve the problem.

1. Read and reread the the scenario to identify the known and unknown quantities.
   
2. Create expressions and equations from the known quantities and variable(s).
   
3. Substitute the values into the general form of the equation $y = ab^x$.
   
4. Follow the order of operations to solve the problem.
   
5. Interpret the solution in terms of the context of the problem.