CONTAINERS David is designing a cylindrical container. He wants the height of the container to be twice the length of the radius. Write an expression for the ratio of the volume of the container to the surface area of the container, where h is the height and r is the radius.

The distribution of the amount of money spent by students for textbooks in a semester is approximately normal in shape with a mean of $235 and a standard deviation of $20. according to the standard deviation rule, how much did almost all (99.7%) of the students spend on textbooks in a semester?