Consider the diffusion of some hypothetical metal Y into another hypothetical metal Z at 950(C; after 10 h the concentration at the 0.5 mm position (in metal Z) is 2.0 wt% Y. At what position will the concentration also be 2.0 wt% Y after a 17.5 h heat treatment again at 950(C? Assume pre-exponential and activation energy values of 4.3 ( 10-4 m2/s and 180,000 J/mol, respectively, for this diffusion system?