4 The random variable \(X\) takes the values \(- 1,1,2,3\) only. The probability that \(X\) takes the value \(x\) is \(k x ^ { 2 }\), where \(k\) is a constant.
- Draw up the probability distribution table for \(X\), in terms of \(k\), and find the value of \(k\).
- Find \(\mathrm { E } ( X )\) and \(\operatorname { Var } ( X )\).