Mary unknowingly overdrew her checking account by $67. Mary then deposits $112, writes a check for $103 and then let’s her friend borrow $55. What is the balance in her account now?

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.