Calculating Maximum Bending Stress of a Beam

[MMCS]

A uniform simply supported beam, 5 m long and having a cross-section as shown, is to support a load which varies linearly from zero at the left hand support to a magnitude of 20 kN/m at the right hand support. Determine the position and magnitude of the maximum bending stress.
ANS : 140 MPa, 2.89 m from left

Total load w*L/2 = 50,000
Load at distance x (w*x)/L

I know that distance of maximum load = L/sqrt3 = 2.89

So the maximum bending moment = (20,000*2.89)/5 = 11560

I have out this into the formula M*Y/I =σ but get an incorrect answer

Unfortunately the picture with dimensions is unable to upload but it is an I beam with a second moment of area as 0.00003813 and a distance from the neutral axis as 0.1

Thanks

 

[SteamKing]

It would be nice to know what your incorrect answer was.

 

[haruspex]

So the maximum bending moment = (20,000*2.89)/5 = 11560

I agree with the 2.89 but not the 11560 (I get 32075). What's the rationale for that equation?