ER Model

Consider an Entity-Relationship (ER) model in which entity sets $E_1$ and $E_2$ are connected by an $m:n$ relationship $R_{12}$. $E_1$ and $E_3$ are connected by a $1:n$ (1 on the side of $E_1$ and $n$ on the side of $E_3$) relationship $R_{13}$. $E_1$ has two single-valued attributes $a_{11}$ and $a_{12}$ of which $a_{11}$ is the key attribute. $E_2$ has two single-valued attributes $a_{21}$ and $a_{22}$ of which $a_{21}$ is the key attribute. $E_3$ has two single-valued attributes $a_{31}$ and $a_{32}$ of which $a_{31}$ is the key attribute. The relationships do not have any attributes. If a relational model is derived from the above ER model, then the minimum number of relations that would be generated if all the relations are in 3NF is _____.

Given an instance of the STUDENTS relation as shown below: $$\begin{array}{|l|l|l|c|c|} \hline \textbf{StudentID} & \textbf{StudentName} & \textbf{StudentEmail} & \textbf{StudentAge} & \textbf{CPI} \\ \hline 2345 & \text{Shankar} & \text{shankar@math} & X & 9.4 \\ 1287 & \text{Swati} & \text{swati@ee} & 19 & 9.5 \\ 7853 & \text{Shankar} & \text{shankar@cse} & 19 & 9.4 \\ 9876 & \text{Swati} & \text{swati@mech} & 18 & 9.3 \\ 8765 & \text{Ganesh} & \text{ganesh@civil} & 19 & 8.7 \\ \hline \end{array}$$ For (StudentName, StudentAge) to be a key for this instance, the value X should NOT be equal to _____.