The list price of an item is $72.96. The supplier is offering a series trade discount of 13 divided by 12/20. Find the net cost.

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.