Grace was out at a restaurant for dinner when the bill came. Her dinner came to $33. After adding in a tip, before tax, she paid $38.61. Find the percent tip.

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?

Solve each quadratic equation by factoring and using the zero product property. x^2 + 18x = 9x

The area of a circle is equal to 1 dm². find the radius of the circle.