If the primary/secondary resistance rate is 1/16; What is the winding turns ratio ?

Well it is known that:

Vp/Vs = Np/Ns

Is/Ip = Np/Ns

Then Vp/Vs * Is/Ip = (Np/Ns) * (Np/Ns) = (Np/Ns)^2

(Vp*Is)/(Vs*Ip) = (Np/Ns)^2

Vp/Ip * Is/Vs = (Np/Ns)^2

Rp *1/Rs = (Np/Ns)^2

Rp/Rs = (Np/Ns)^2

1/16 = (Np/Ns)^2

Np/Ns =1/4 

from the formula for turns ratio of transformer R1/R2= (T1/T2)2 

therefore turns ratio will be1/256.