Errors in Measurement question from JEE Main 2016

Answer: (c)

1. Mean $= \frac{90 + 91 + 95 + 92}{4} = \frac{368}{4} = 92\text{ s}$
2. Absolute deviations: $2, 1, 3, 0$; mean absolute error $= \frac{6}{4} = 1.5\text{ s}$
3. The clock reads only to 1 s, so the error is rounded to $2\text{ s}$: $92 \pm 2\text{ s}$.
4. So the answer is (c) $92 \pm 2$ s.