Circuit Problem: MCAT physics

[premedsp]

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This question is relating to a video from the Premed HQ channel (youtube channel).

How is the answer 4 ohms? I see the series at the top which equals 4 ohms. That series is then in combination with the parallel resistor and gets us 1/2 ohms. I not sure where to go from there.


Video credit:

 

[FrameshiftAndrew]

This is a really easy mistake to make 🙂. The total resistance term for the circuit component on top isn't 1/2 ohms, it is 1 over (2 ohms), since the equation is 1/R1 + 1/R2 = 1/Rtotal. I attached a screenshot with more intuitively aligned equations, which should help make this clear.

 

[premedsp]

Oh I see.
Thanks Andrew