Background: This problem refers back to Problem 4 of the previous problem set. It helps to complete your physical picture of the ``flow'' of probability.
Use the probability current to
compute as a
function of time t the rate 
at
which probability flows across the point 
from the left half to
the right half of the square well in Problem 4 of Problem Set 5.
Integrate your result from
t=0 to 
and compare with your answer for
4.3 of Problem Set 5.