Question

The mean of 200 items was 50. Later on, it was discovered that two items were misread as 92 and 8 instead of 192 and 88. find the correct mean.

Answer 1

Since,

Mean of 200 items = 50

$\frac{sumof200items}{No.ofitems}=mean$

sum of 200 items = mean of x no of items

$50\times 200=10,000$

wrong sum of 200 items = 10,000

Correct sum = 10,000+192+88-92-8

= 10,280-100

=10,180

$\therefore$ correct mean = $\frac{10,180}{200}$

= 50.9