Faster runner, slower runner
Two runners start on a straight one-mile race track. The slower runner S is given a handicap and starts first. The faster runner F then starts and after 4 minutes of running, he passes S. After a further 2 minutes, in which time the faster runner has run to the end of the track and immediately turned back, the runner pass each other again (going in opposite directions). After a further 7 minutes, in which time each has run to an end of the track (opposite ends) and immediately turned around, they met once again.
Assuming that their speeds are constant, how long does it take each of then to run one-mile?[email_link]http://solvemaths.in/faster-runner-slower-runner/AptitudeContest