Question

the average marks obtained by a class of 70 students was found to be 65. later on it was detected that the marks of 1 students who was wrongly recorded as 85 instead of 58 .find the correct mean.

Answer 1

let find total marks
average marks = total marks/no. of students
65=total marks/70
total marks=4550
He record 85 marks
without his marks total marks are
4550-85=4465
now add correct marks and divide it by 70
4565+58=4623
4623/70 is the correct mean

Answer 2

Answer:

The correct Average or Mean mark of the class is 64.6.

Explanation:

Given that:

Total number of students = 70;

Incorrect mean value = 65;

First of all, let's find the total marks obtained by all the students;

So,

Average or Mean marks =

(Total marks obtained by the student) ÷ (Number of students)

Substituting the values:

⇒65 =   (Total marks obtained by the student) ÷ (70)

⇒ Total marks obtained by the student = 4550;

Now, according to the question:

The marks of one student were wrongly recorded as 85;

So, Removing the marks of that student, we get 4550 - 85 = 4465;

Now, adding the correct marks, that is 58;

⇒ 4465 + 58 = 4523;

Now,

The correct Average or Mean marks = (4523) ÷ 70.

The correct Average or Mean mark = 64.6

Therefore,

The correct Average or Mean mark = 64.6.

To learn more about the mean, visit:

https://brainly.in/question/1570408

To learn more about average, visit:

https://brainly.in/question/49179699

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