If a beam can hold 2,000 pounds at 15 feet, what is the safe load if the length of the beam is 10 feet?

Let's see how many pounds can a one foot I-beam handle. If a 15 feet I-beam can handle 2000 pounds, then a one foot I-beam can handle 1/15 of that weight.

2000 *  = 133 1/3

So, for every extra foot, it can handle an additional 133 1/3 pounds.

Now we want to find out how many pounds a 10 feet I-beam can handle. 

10 *  = 4000/3 or 1333 1/3 pounds

So, a 10 feet I-beam can handle 1333 1/3 pounds.