Question 9
A two-minute sand timer consists of two identical cubes. When all its sand is in one cube, that cube is half full. After sand has flowed for 20 seconds, the layer in the lower cube is 1 cm deep. What is the total sand volume?
Editorial model: Sand flows at constant volume per second, starts entirely in the upper cube, and forms a level layer. A dot between numbers in the original choices means multiplication.
Editorial model: Sand flows at constant volume per second, starts entirely in the upper cube, and forms a level layer. A dot between numbers in the original choices means multiplication.