Question

The calculated mean of 50 observations was 80. It was later discovered that observation 19 was recorded by mistake as 91. What was the correct mean?

Answer 1

It was later discovered that observation 19 was recorded by mistake as 91. What was the correct mean?

We have,

The calculated mean of 50 observations was 80.

$\Rightarrow$ The total incorrect sum of the observations = $80\times 50=4000$

$\Rightarrow$ The total correct sum of the observations $=4000-19+91=4072$

So, the correct mean $=\frac{4072}{50}=81.44$