-21, -18, , -12, , , -3, , 3, 6, , , 15, 18, find the missing numbers

Jackson drew 4 hearts and 29 circles. what is the ratio of circles to all shapes?

Add or subtract polynomial : –12qr? +13rq?

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.