Whenever I try to do this question I always get a really high number...I don't know what I'm doing wrong. Can someone please help?

Here is a graph of the function:

http://imagizer.imageshack.us/v2/800x600q90/826/zebj.jpg

Estimate the total area under this curve on the interval [0, 12] with a Riemann sum using 36 equal subdivisions and circumscribed rectangles. Hint: use symmetry to make this problem easier.

57.340

86.634-- my answer

14.439

49.914

28.044