Monthly savings (in ₹) of 60 members of a self-help group, given as a "more than" table:
more than 100: 60, more than 150: 52, more than 200: 34, more than 250: 16, more than 300: 6.
Find the mean monthly saving.

Differencing downwards gives 100-150: 8, 150-200: 18, 200-250: 18, 250-300: 10, 300-350: 6 (total 60). Class marks 125, 175, 225, 275, 325 give $\sum f_i{x}_i=1000+3150+4050+2750+1950=12900$, so mean $=\frac{12900}{60}=₹215$. "190" uses the lower limits as $x_i$; "182.14" treats the "more than" totals as class frequencies (that makes $\sum f_i=168$, not 60); "2580" divides by the 5 classes.