GATE 2017 ME (ME2) – Question 34
Linear dimensions P and Q have standard deviations 3 and 4 μm. When assembled, the standard deviation of P+Q is ______ μm.
Practise this question in The GATE Grind →
Show answer and explanation
Correct answer: 5 to 5
Explanation
For independent dimensional variations, variances add: σ(P+Q)²=3²+4²=25µm². Taking the square root gives **5µm**. Adding standard deviations directly would give a worst-case type bound rather than the statistical standard deviation.