Concept:
Average/Mean: Mean of 'n' observations = \(\rm \overline x=\frac{\text{Sum of Observations}}{n}\).
Calculation:
Here, the final number of students is 200 (no change).
The change in the value is: (43 - 34) + (35 - 53) = 11 - 18 = -7.
Using Averagenew = Averageold + (Average of change), we have:
Averagenew = 40 + \(\left(\frac{-7}{200}\right)\)
= 40 - 0.035
= 39.965