Inversely proportional

Have I done this correctly?

f is inversely proportional to d

when d=50, f=256
Find value of f when d=80

Figured out a constant of 25/125

so

f=50/1*125/25=250

Is thsi correct?

its incorrect
since f is inversely proportional to d we have
f=k/d where k is a constant
now as f=256 when d=50 then
k=fd=50*256
so value of f when d=80
f=(50*256)/80=160

f is inversely proportional to d ...



... where k is the constant of proportionality.


substitute in the given values to solve for k ...







... finish the problem

ah I did d/k.

Thanks.