Which expression is equivalent to 2 2
-- + --
b a

2
—-
ab

Monthly water bills for a city have a mean of $108.43 and a standard deviation of $32.09. find the probability that a randomly selected bill will have an amount greater than $155, which the city believes might indicate that someone is wasting water. would a bill that size be considered unusual?

Give the equations of two different lines that are perpendicular to the line 3x + 4y = 7.

The radius of the earth is two times the radius of the moon. what fraction of the volume of the earth is the volume of the moon?