The probability that event \(A\) will occur in the \(i\) th trial is \(p_{i}\). Let \(\mu\) be the number of occurrences of \(A\) in the first \(n\) independent trials. Find

(a) \(M \mu\),

(b) \(\mathbf{D}_{\mu}\),

(c) \(M\left(\mu-\sum_{1}^{n} p_{i}\right)^{3}\) and

(d) \(M\left(\mu-\sum_{1}^{n} p_{i}\right)^{4}\)