Margaret and Bethany have a lemonade stand for one week each summer. Each day they spend $1.50 on the ingredients necessary to make 20 cups
of lemonade. They sell each cup of lemonade for $0.25. How much do the
girls, after expenses, earn on a day that they sell 18 cups of lemonade? *
$6.00
$4.50
$3.50
$3.00

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.