first thing you want to do is convert his speed:
given speed - 8 min/mile
converted - 1/8 miles/min
He has only 50 mins more to run at this speed, thus:
distance to be covered: Speed x Time : 50 x 1/8 = 6.25 miles
Now, total distance = 3.25 + 6.25 = 9.5 miles
This is his distance covered north and south equally. Thus one way distance would be half of this - 9.5/2 = 4.75
Thus the distance that is remaining to be covered south = 4.75 - 3.25 = 1.5 - Answer@
given speed - 8 min/mile
converted - 1/8 miles/min
He has only 50 mins more to run at this speed, thus:
distance to be covered: Speed x Time : 50 x 1/8 = 6.25 miles
Now, total distance = 3.25 + 6.25 = 9.5 miles
This is his distance covered north and south equally. Thus one way distance would be half of this - 9.5/2 = 4.75
Thus the distance that is remaining to be covered south = 4.75 - 3.25 = 1.5 - Answer@