3. In a test studying reaction times, white dots appear at random on a black rectangular screen. The continuous random variable \(X\) represents the distance, in centimetres, of the dot from the left-hand edge of the screen. The distribution of \(X\) is rectangular over the interval [0,20].

1. Find \(\mathrm { P } ( 2 < X < 3.6 )\).
2. Find the mean and variance of \(X\). The continuous random variable \(Y\) represents the distance, in centimetres, of the dot from the bottom edge of the screen. The distribution of \(Y\) is rectangular over the interval [ 0,16 ]. Find the probability that a dot appears
3. in a square of side 4 cm at the centre of the screen,
4. within 2 cm of the edge of the screen.