Suppose we would like to approximate the the shaded region R in the following diagram, using four rectangles of equal width, and right endpoints. 14 - - -10 -9 f. (x ) - -5 R - a Answer the following question with an integer. (a) What is the height of the third rectangle? (b) What is the area of the fourth rectangle? (c) What is the approximated area? (d) Using Part (c), what is the approximated average value of f (x) on the interval [0 , 4]