Question

11. the mean score of 40 students was found to be 87.5. later on, it was observed that the score of one of the students was recorded as 88 instead of 68. Wh
at should be the correct mean score?

Answer 1

Given:

• Wrong Mean of 40 obs.=87.5
• Wrong obs.=88
• Right obs.=68

To find:

• Right Mean

Solution:

Difference between wrong and right values+88-68=20

Wrong Sum of Observations=87.5×40=3500

Right Sum of 0bservations=3500-20=3300

Mean=3300/40=82.5

The correct mean score is 82.5