Question

a construction worker measures the amount of cement in a cement truck every 5 minutes as it empties what is the rate of change for the volume of cement in the truck

Answer 1

That's exactly what he's measuring.  So we can't tell,
because you haven't told us any of his measurements.

The rate of change during any 5-minute period would be

   (the difference between two of his measurements)
divided by
   (5 minutes)

                 probably in units of  [cubic yards per minute].