Electrochemistry Question from USNCO
Given these standard reduction potentials, what is the standard reduction potential for $$ \ce{Co^{3+}(aq) +3e- -> Co(s)} $$

Given:

\begin{align} \ce{Co^{3+}(aq) + e- &-> Co^{2+}(aq)} & E° &=1.82~\mathrm{V}\\ \ce{Co^{2+}(aq) + 2e- &-> Co(s)} & E° &=-0.28~\mathrm{V}\\ \end{align}

When you add them up to get the net equation, you get $1.54~\mathrm{V}$. But the correct answer is $0.42~\mathrm{V}$!

Am I missing something?

Given:

\begin{align} \ce{Co^{3+}(aq) + e- &-> Co^{2+}(aq)} & E° &= \pu{+1.82 V} \\ \ce{Co^{2+}(aq) + 2e- &-> Co(s)} & E° &= \pu{-0.28 V} \end{align}

what is the standard reduction potential for $\ce{Co^{3+}(aq) +3e- -> Co(s)}$?

If I add up these two half-equations to get the desired half-equation, I get $E^\circ = \pu{+1.54 V}$. But the correct answer is $\pu{+ 0.42 V}$!

Am I missing something?

Given these standard reduction potentials, what is the standard reduction potential for $$ \ce{Co^{3+}(aq) +3e- -> Co(s)} $$

Given:

$$ \ce{Co^{3+}(aq) + e- -> Co^{2+}(aq)} \ \ \ E°=1.82 V $$ $$ \ce{Co^{2+}(aq) + 2e- -> Co(s)} \ \ \ E°=-0.28 V $$

When you add them up to get the net equation, you get 1.54 V. But the correct answer is 0.42 V!

Am I missing something?

Electrochemistry Question from USNCO
Given these standard reduction potentials, what is the standard reduction potential for $$ \ce{Co^{3+}(aq) +3e- -> Co(s)} $$

Given:

\begin{align} \ce{Co^{3+}(aq) + e- &-> Co^{2+}(aq)} & E° &=1.82~\mathrm{V}\\ \ce{Co^{2+}(aq) + 2e- &-> Co(s)} & E° &=-0.28~\mathrm{V}\\ \end{align}

When you add them up to get the net equation, you get $1.54~\mathrm{V}$. But the correct answer is $0.42~\mathrm{V}$!

Am I missing something?