Part B, using correct units, explain the meaning of the definite integral, so it's the definite integral from zero, from t equals zero to t equals 40, the absolute value v of t, dt, in the context of the problem. Approximate the value of that integral using a right Riemann sum with the four subintervals indicated in the table. All right, so let's first tackle the first part. So what's the meaning of this definite integral? So the velocity, velocity is a vector, it has direction. And you can see, when you look up here, that sometimes the velocity is positive and sometimes it is negative. And a reasonable interpretation of that is, well, this is when she's walking in one direction and then that's whatever direction we assume is the positive direction, and this is when she's walking the other way.