Question

The mean of 100 items was found to be 30 are the timer for calculation to items were wrongly taken as 32 and 12 instead of 23 and 11 find the correct mean

Answer 1

As we have given mean and n
therefore we have to take out the sum of all the observations(x)
that is
x = mean × n
x= 30 ×100
x = 3000
now add the correct no. which were misread that is
add 23 and 11
and you will get
3034
now subtract the wrong no. that is
sub 32 and 12 from 3034
that will give you 2990
now it is your new sum of observations
therefore new mean will be
2990/100
=29.9