What are the in-degree and out-degree of vertex 4? 
What is the minimum number of colours required to colour the following graph?

The supply voltage magnitude \( |V| \) of the circuit shown below is ____ .
A two-port network is defined by the relation
\(\text{I}_1 = 5V_1 + 3V_2 \)
\(\text{I}_2 = 2V_1 - 7V_2 \)
The value of \( Z_{12} \) is: