4. Use the graph below to select the number that most likely estimates the integral fo f(t) dt. -37, - 20, - 10, 2.7, 31, 38.3, 40.1, 13. Use the graph to determine whether each expression is positive, negative, zero, or there is not enough in- formation to decide. 40- At) 30+ 20+ 7 . Ax. 10- .2 0.5 4 (a) fof(x) da (b) Is (f(x) -6) dx (a) 15x - 8| de (c) ff(z +3) dx (d) fo f(x) dx (b )