Abathtub that holds.32 gallons of water contains 12 gallons of water .you begin filling it and after 5 min the tub is full

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.