Question

A 15 ft plank of mass 50 kg is laid across two ladders. The ladders are 5 ft apart, and the plank is laid such that 5 ft of it hang off at each end. You have a mass of 90 kg.

(a) How far out past the ladder can you walk before it gets dangerous?

I tried doing

m1r1=m2r2

(33.33)(5)=(90+16.6)r2

and sloved for r2= 1.56, but the computer keeps saying its wrong.