>>>Run for 6 min 59 sec's than turn around and walk.
>>
>>Exactly. The guard, following his instructions, will then "send him back" - out of the country.
>
>This is one that I figured out on my own. However I would recommend 6 minutes and 30 seconds.
>
>Peter

See my reply - if he turned after running 5 minutes & continued running, he would arrive at the point he would have done if he'd run 7 minutes from the opposite side.