Let $X_t$ be a weak stationary process ARMA(1,1)
$X_t=c+\phi X_{\left(t-1\right)}+\theta\varepsilon_{\left(t-1\right)}+\varepsilon_t$
$\varepsilon_t$ ~ $WN\left(0,\sigma^2\right)$
The estimated parameters are:
$c=-4$
$\phi=-0,5$
$\theta=-0,3$
$\sigma^2=0,12$
If I have to compute the expected value of $X_t$, is correct to say that the mean of ARMA(1,1) (if stationary) is equal to the mean of AR(1)?
If I follow this statement, $E(X_t)$ should be:
$E\left(X_t\right)=c/\left(1-\phi\right)\cong-2.67$
Is there something wrong?