Question 2
Alice, Betty, Carl, David and Elva attend the same school. When walking alone, each person moves at a speed of 2.0 m per second. When walking in a group, their speed depends on the group size: any pair walks at 1.5 m/s, any trio at 1.0 m/s and any quartet at 0.5 m/s. One day, Alice and Betty leave the school together at 16:00:00, Carl at 16:01:00, David at 16:02:00 and Elva at 16:03:00. They all walk in the same direction along a straight road and whenever someone catches up with another, they join the group immediately. How far, in m, from the school will they be when all five of them are together?