7 A random variable \(X\) has the distribution \(\operatorname { Po } ( 1.6 )\).
- The random variable \(R\) is the sum of three independent values of \(X\). Find \(\mathrm { P } ( R < 4 )\).
- The random variable \(S\) is the sum of \(n\) independent values of \(X\). It is given that
$$\mathrm { P } ( S = 4 ) = \frac { 16 } { 3 } \times \mathrm { P } ( S = 2 )$$
Find \(n\).
- The random variable \(T\) is the sum of 40 independent values of \(X\). Find \(\mathrm { P } ( T > 75 )\).