Question

.a person while calculating the average marks of 50 students of a class by mistake entered a value as 45 instead of 54 and gets the average as 63. find the actual average of the class.

Answer 1

According the question total number of students=50

Wrong average=63

Now total marks obtained by all the students of the class= 63 × 50=3150

This is in accordance to the data that has the mistake.

Now let's correct the mistake…

Subtract the incorrect score from the total.

$3150- 45=3105$

Now this the correct total of all the other students. Now, to get the actual total of the class add the unfortunate student's score to the total of the rest of the class.

$3105 + 54=3159$

This is the correct total marks of the class. To find the average divide the total by the number of students in the class. Thus we get,

3159 ÷ 50 =63.8

Ans :- The actual average of the class will be 63.8