The graph of a function f(x) is given below. Use the midpoint Riemann sum with 4 sub-intervals to approximate the area under the curve over the interval [2,6]. YA 15 14 13 . ....... 12 ...... . ...... 10 . . ..... .... . .. . . ... 2 3 4 5 6 X 37 33 31 O29 28