Average marks of 30 students were 40. Later on it was found that a score 47 was misread as 74. Find the correct average.
Answers
Answer:
Step-by-step explanation:
Average = Sum of all observations/
Total no. of observations
=> 40 = x/30
=> 40*30 = x
=> 1200 = x
Correct sum = 1200-74+47
=> 1173
New average = 1173/30
=> 39.1
The correct average is 39.1
Given : Average marks of 30 students were 40. Later on it was found that a score 47 was misread as 74.
To find : The new average.
Solution :
We can simply solve this mathematical problem by using the following mathematical process.
Average marks of 30 students = 40
So,
Total marks of 30 students :
= Average marks of 30 students × Number of students
= 40 × 30
= 1200
Now,
47 was misread as 74
The invalidly increased marks = 74-47 = 27
Correct total marks :
= Previous total marks - Invalidly increased marks
= 1200 - 27
= 1173
Correct average marks :
= Correct total marks ÷ Number of students
= 1173 ÷ 30
= 39.1
(This will be considered as the final result.)
Hence, the correct average is 39.1