Exercises, 5.3.70, 5.5.44, 5.5.62 were graded out of 3 points each. The last point was awarded if the other problems looked okay.
A lot of students had trouble with 5.3.70: read the chapter of the book on Riemann sum again, and try to remember how we get from an integral to its Riemann sum representation and back. In that case, the key was to recognize that the limit was just the integral from 0 to 1 of the square root of x.