In problem #5 what was george’s velocity in meters per second?

Your calculation of George's SPEED is correct.  Nice work !

Velocity is different.  Here's how to do velocity:

Velocity = (displacement) / (time)

Displacement = (distance and direction from start-point to end-point)

George ended 500 meters North of where he started.  So his displacement is 500 meters North.

Velocity = (500 meters North) / (13 seconds)

Velocity = 38.46 m/s North

Explanation:

As we know that velocity is defined as the ratio of total displacement of the object and total time taken by it

So here we know that

here we have

d = 750 (North) + 250 (South) m

m North

time taken by him is given as

now we have