Okay, first of all, read the 500 other posts with the same question. Second, do a search for "beam deflection calculation." This is one of the simplest static force calculations out there, particularly since the problem gave you all of the info you need - you just need to plug it in to the correct equation. Here is a link:
Link
But just in case you are having a problem, here is the calculation:
D = WL^3/48EI
Where:
D = Deflection (in)
W = weight of load on the beam (pounds)
L = length of beam (inches)
E = modulus of elasticity of the beam (lb/in^2)
I = moment of inertia (in^4)
So, given the information you've got in the problem:
D = 6000*(50*12)^3/48*29,000,000*850 = 1.1 inches
Next time, since a whole bunch of people post the same blasted "riddle" read those posts before you post it AGAIN.