\textbf{181-} What is the minimum number of $4\,\Omega$ resistors that must be connected together so that, from a $12\,\text{V}$ power source, an electric current of $15\,\text{A}$ is obtained?
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(1) $3$ \hfill (2) $4$ \hfill (3) $5$ \hfill (4) $6$
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