Here's the question you clicked on:
nexis
MV Calculus: Check the integral on p.2, the first example at: http://ocw.mit.edu/courses/mathematics/18-02sc-multivariable-calculus-fall-2010/3.-double-integrals-and-line-integrals-in-the-plane/part-a-double-integrals/session-51-applications-mass-and-average-value/MIT18_02SC_notes_25.pdf Assuming M=1, i got 1/6 for xcm. Is this wrong?
look at all the high level users here
x cm =1/6 looks ok for M=1, but in the example M= 1/4