Q.If, in the previous question, each worker is given a hike of 10% in wages, how are the mean and standard deviation values affected?

Multiplying every value by the same factor scales both the average and the spread by that factor — standard deviation is not independent of scale. …

A 10% hike multiplies every wage by the factor 1.1.

Mean. The mean is scaled by the same factor: new mean $= 200 \times 1.1 = ₹220$.

Standard deviation. Standard deviation is not independent of scale — multiplying every value by 1.1 multiplies the deviations, and hence the standard deviation, by 1.1: new S.D. $= 40 \times 1.1 = ₹44$. …