The function f is continuous on the interval [4, 15], with some of its values given in the table above. Estimate the average value of the function with a Right Rectangle Approximation, using the 4 intervals between those given points.
x 4 9 11 14 15
f(x) -6 -11 -18 -21 -25
-11.545
-14
-16.273
-18.75
I really need help with this question, it is the hard problem in my set and i'm not able to get it.