The jurisdiction of the rescue team includes emergencies occurring on a stretch of river that is 4 miles long. Experience has shown that the distance along this stretch, measured in miles from its north most point, at which an emergency occurs can be represented by uniformly distributed used random bearable over the range is 0 to 4 miles. The rescue team's base is at the midpoint of the stretch of river, find the probability that a given emergency arises more than 1.8 miles from this base.