Which expression is equivalent to StartRoot StartFraction 55 x Superscript 7 Baseline y Superscript 6 Baseline Over 11 x Superscript 11 Baseline y Superscript 8 Baseline EndFraction EndRoot? Assume x > 0 and y Greater-than 0.

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.