According to the laws of diffusion, the time it takes for a substance to diffuse is proportional to the square

Question

of the distance. If a substance requires 3 seconds to diffuse 10 mm, how long will it take to diffuse 20 mm? Please, explain your answer.

Answer 1

if time is proportional to the square of the distance then you can write:
t is proportional to d^2
then:
3 seconds is proportional to 10^2
So
x seconds is proportional to 20^2
3-----> 100
x------>400
x= (400x3)/100
x= 12 seconds