Exponential and logarithmic models

A sum of money is invested in a fund. Its value, in dollars, is modelled by $V = V_0 k^t$, where $V_0$ and $k$ are constants and $t$ is the time in years. The value is $5000$ after 3 years and $8000$ after 7 years. Find the value of $k$, correct to 3 significant figures.