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# What is the value of the third resistor?

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Reputation ## What is the value of the third resistor?

A three-branch parallel circuit has a total resistance of 385.83 ohms. Two of the resistors are 680 ohms and 1500 ohms. What is the value of the third resistor?
Why is this wrong 2.  Junior Member Pro Subscriber
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Reputation  Originally Posted by samfulton A three-branch parallel circuit has a total resistance of 385.83 ohms. Two of the resistors are 680 ohms and 1500 ohms. What is the value of the third resistor?
Why is this wrong
Let x = third resistor
1/R1 + 1/R2 + 1/R3 = 1/Rtotal
Rearrange the equation
1/Rtotal - 1/R1 - 1/R2 = 1/R3
1/358.83 - 1/680 - 1/1500 = 1/x
When solved x = 2200 ohm 3.  Junior Member Pro Subscriber
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Reputation  Originally Posted by kwegley Let x = third resistor
1/R1 + 1/R2 + 1/R3 = 1/Rtotal
Rearrange the equation
1/Rtotal - 1/R1 - 1/R2 = 1/R3
1/358.83 - 1/680 - 1/1500 = 1/x
When solved x = 2200 ohm
I believe this is incorrect, can you actually demonstrate your calculations! electrical calculations, electrical theory, neta exam questions, neta level 2  