X Consider the graph of y = / f(t) dt, where fis a piecewise constant function. 0 (a) Over which intervals is fpositive? (Enter your answer using interval notation. If an answer does not exist, enter DNE.) Over which intervals is it negative? (Enter your answer using interval notation. If an answer does not exist, enter DNE.) Over which intervals, if any, is it equal to zero? (Enter your answer using interval notation. If an answer does not exist, enter DNE.) What are the maximum and minimum values of 1"? maximum value minimum value What is the average value of fever [0, 6]