On the last page, every time we multiplied distance by 10, the time to diffuse increased 100-fold!
10 times as far –> 100 times as much time
What’s going on here? If time to diffuse was directly proportional to distance, then 10 
times the distance would require 10 times as long — not 100.
This over-inflation is like if you went to McDonald’s to buy 10 hamburgers and they charged you 100 times (not 10 times) the price of a single hamburger. Not fair? Well, that means time to diffuse is not directly proportional to distance.
photo credits: mcDonalds