Question

the average score of a class having 60 students was miscalculated to be 45.During investigation, it was found that the scores of 2 students was misread as 45,56 in lieu of 24 and 86.find the correct average​

Answer 1

Total number of students = 60

Average score (old) = 45

Sum of all observations will be :-

= 60 * 45

=2700

Miscalculations :-

(i) 45 was miscalculated as 24

Difference = 24-45 = (-21)

(ii)56 was miscalculated as 86

Difference = 86 - 56 = 30

Net difference in sum will be :-

$30 - 21 \\ \\ = 7$

$\rule{200}{2}$

New sum of observations = 2700 +7

= 2707

$\rule{200}{2}$

Average = 2707/60 = 45.116

$\rule{200}{2}$

Answer 2

Step-by-step explanation:

Total number of students = 60

Average score (old) = 45

Sum of all observations will be :-

= 60 * 45

=2700

Miscalculations :-

(i) 45 was miscalculated as 24

Difference = 24-45 = (-21)

(ii)56 was miscalculated as 86

Difference = 86 - 56 = 30

Net difference in sum will be :-

\begin{lgathered}30 - 21 \\ \\ = 7\end{lgathered}

30−21

=7

New sum of observations = 2700 +7

= 2707

Average = 2707/60 = 45.116