Ireplaced a square window with a retangular one the new window is 3ft wider and 2ft higher than the square one it has an area of 42ft how long was the side of the original square window

The coverage of a base station of a telecommunication company forms a disk with a radius of (kilometers). let be the distance of a cellphone from a base station. assume that the location of cellphones in use are randomly uniformly distributed within the disk. calculate the mean and variance for the random variable.