Sometimes circuits have a combination of series and parallel. The technique here is the same as the previous sections; you just need to look at it in steps. Try finding the total resistance of the following circuit.

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Hint #1

Simplify the parallel resistors first, and then put that result in series with the other two.

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Hint #2

Identify known variables:	R1 = 100Ω, R2 = 150Ω
Equation:	1 RT = ∑ 1 Ri
Substitute values to get:	1 RT = 1 100 + 1 150
Least common denominator is 300	1 RT = 3 300 + 2 300
	1 RT = 5 300 RT = 300 ÷ 5 RT = 60Ω

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Hint #3

Put the result you just got in series with the other two resistors:

Identify known variables:	R1 = 68Ω, R2 = 82Ω R3 = 60Ω
Equation:	RT = R1 + R2 + R3
Substitute values and solve:	RT = 68Ω + 82Ω + 60Ω = 210Ω

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Check Your Answer

R_T = 210Ω