A standard problem in high-school algebra is to determine how long it will take several workers to complete a job if the individual times required to complete the job are known.
This Demonstration lets you explore the relationship between the individual times needed and the time needed by the group working together.
You can set two, three or four workers and the individual times, which range from 1/2 hour to 6 hours in half-hour increments. For each option of the number of workers, the computation of the time required for the group is given.
You can also solve a related problem in which an individual time is to be calculated from the group time.