Question e44ce79d

$P\left(t\right)=290{\left(1.04\right)}^{\left(\frac{4}{6}\right)t}$

The function $P$ models the population, in thousands, of a certain city $t$ years after $2005$. According to the model, the population is predicted to increase by $n\%$ every $18$ months. What is the value of $n$?