A student walks 4 block east, 7 blocks west, 1 blocks east then 2 blocks west in an hour. Her average speed is block/hour

Average speed = (total distance) / (total time)

Average speed = (4+7+1+2 blox) / (1 hour)

Average speed = 14 blocks/hour

I'm gonna go out on a limb here and take a wild guess:

I'm guessing that there's another question glued onto the end of this one, and it asks you to find either her displacement or her average velocity.  I'm so sure of this that I'm gonna give you the solution for that too.  If there's no more question, then you won't need this, and you can just discard it.  I won't mind.

Average velocity = (displacement) / (time for the displacement)

"Displacement" = distance and direction from the start point to the end point, regardless of how she got there.

Displacement = (4E + 7W + 1E + 2W)

Displacement = (5E + 9W)

Displacement = 4 blocks west

Average velocity = (4 blocks west) / (1 hour)

Average velocity = 4 blocks/hour  West

the answer is b, have negligible mass