Question

Arithmetic mean of nine observations is calculated as 38. But in doing so, mistakenlythe observation 27 is taken instead of 72. Find the actual mean of the data.​

Answer 1

Actual Mean = 43

Explanation:

Given Mean = 38

No of observations = 9

we know,

Mean = Sum / N

38 = Sum/ 9

Sum = 38 x 9 = 342

Since the observation 27 was mistakenly taken instead of 72, we subtract 27 from the sum and add 72.

New sum = 342 - 27 = 315 again, 315 + 72 = 387

The no. of observations stays the same.

Actual mean = New Sum / N

= 387/9

=43

Answer 2

Explanation:

arithmetic mean =38

n=9

mean=sum/n

sum=mean×n=38×9=342

mistakenly observation 27 is taken instead of 72

new sum becomes =342+72-27=387

now

new mean =new sum/n=387/9=43

the actual mean of the data is 43.