Question

The mean of marks of 40 students is 56.5. Later it was found that one student was given 85 marks instead of 58. Find the correct mean.

Answer 1

Answer:

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