Two resistance 100Ω ± 5Ω and 150Ω ± 15Ω are connected

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Two resistance 100Ω ± 5Ω and 150Ω ± 15Ω are connected in series. If the errors are specified as standard deviations, the resultant error will be:

1. ± 10Ω
2. ± 10·6Ω
3. ± 15·8Ω
4. ± 20Ω

Correct Option: C

Given, R₁ = 100Ω ± 5Ω
R₂ = 150Ω ± 15Ω
R_T = R₁ + R₂ (as they are connected in series)
There errors are specified at standard deviations are probable errors. In this case the resultant error.
R = √± R₁² + R₂²
= √± 5² + 13²
= ± 15·8Ω