Considera sample of 50 observations from a stationary process with 

   $$\begin{array}{c|c|c|} 
 \text{lag} & \text{acf} & \text{pacf}  \\ \hline
1 & 0.9 & 0.9 \\ \hline
2& 0.85 & 0.4\\ \hline
3&0.7&0.1\\ \hline
\end{array}$$
    
How do I suggest an appropriate model using the above information.

From my understanding, significance of ACF and PACF values were checked using:$ H_{0}: \rho=0$  rejected at 5% level of significance if $|\rho| >\frac{1.96}{\sqrt(50)}$. I found that only the last value of pacf is non significant. 

(1)Can I say that the model is ARMA(2,3)?
(2) how to decide if it is AR, MA or ARMA?

NB: this was a question asked in an examination. To be worked out manually.