Mathematics

Problem

The following table shows the daily wages (in ₹) of 60 workers in a factory:

Class interval	30–40	40–50	50–60	60–70	70–80
Frequency	8	12	20	15	5

a. (i) Calculate the mean wage by treating the class marks directly. b. (ii) Re-calculate the mean wage after first subtracting 60 from every class mark before multiplying with its frequency, and state whether the mean obtained differs from part (i).

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