Write an explicit formula for a_na n , the n^{\text{th}}n th term of the sequence 6, 12, 18, ...6,12,18,

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.