Resistors combined in series and parallel

 
Two 10 ohm resistors in parallel are combined with the third 10 ohm resistor is series. The calculated total resistance of the combination is 15 ohm (two 10 ohm resistors in parallel = 5 ohm, plus 10 ohm in series). The measured total resistance is 14.8 ohm and 15.2 ohm; in both cases the measurement error is about 1%.