Kelly's art teacher asked him to draw a rectangle with a length of 6 inches and a width of 10 inches. After Kelly does so, his teacher changes her mind and asks him to draw a proportional rectangle that has a length of 9 inches. How many inches wide is the new rectangle?

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.