What cathode potential (versus S.H.E.) is required to reduce 99.99% of Cd(II) from a solution containing 0.10M

Question:

What cathode potential (versus S.H.E.) is required to reduce 99.99% of Cd(II) from a solution containing 0.10M Cd(II) in 1.0 M ammonia if there is negligible current? Consider the following reactions and assume that nearly all Cd(II) is in the form Cd(NH3)₄²⁺.

Cd2+ + 4NH3 Cd(NH,)* 2+ B4 = 3.6 x 10 Cd2+ + 2e = Cd(s) E° = -0.402 V