Alexandra studied 7 pieces by each modern artist featured in the museum. Each artist has the same number of works in the museum. Is this sample of the work of the museum's modern artists likely to be biased?

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.