Nernst potential for K+ ion across the cell membrane is-

Ref:  Guyton & Hall’s ‘Textbook of Medical Physiology’; 10/e,pg55 Contribution of the Potassium DiffusionPotential: We make the assumption that the only movement of ions through the membrane is diffusion of potassium ions. Because of the high ratio of potassium ions inside to outside, 35 to 1, the Nernst potential corresponding to this ratio is -94 mV because the logarithm of 35 is 1.54 and this times -61 mV is -94 mV. Therefore, if potassium ions were the only factor causing the resting potential, this resting potential inside the fiber would also be equal to -94 mV. Now, let us see what Ganong has to say – Ref: Ganong, 23/e, Pg 8, Table 1-1.