In an examination, the average marks of 40 students is 72. Afterwards it is found that the marks of three students are recorded as 68, 65 and 73 instead of 64, 62 and 84 respectively. Find the correct average.

72.1

Increase / decrease in marks =( 64 + 62 + 84 ) - ( 68 + 65 + 73 )

                                          = +4

Avg. of 40 students = 72 + \(\frac{4}{40}\)

                             = 72.1