The average marks of 100 students in a class are 48. But while calculating it, the marks of a student were written 73 instead of 53. Find out the corrected arithmetic mean.
Incorrect $\Sigma $X = N x $\bar { X }$
=100 x 48 =4,800
Correct $\Sigma $X =4,800-73+53=4,780
Hence, Correct $\bar { X }$ =4,780/100=47.8