Question

The mean of marks Scored by $100$ students was found to be $40$. Later on it was discovered that a Score of $53$ was misread as $83$. Find the correct mean.

Answer 1

Mean score = 40
mean=sum of observation /no of observations

sum of observations = mean * no of observations

that is 40 x 100

= 4000
after replacement, sum of new observation=4000-83+53
=3970
mean of new observation = 3970/100
=39.7