Question

find the mean marks of a student from the following cumulative frequency distribution
marks number of students
0 and above 80
10 and above 77
20 and above 72
30 and above 65
40 and above 55
50 and above 43
60 and above 28
70 and above 16
80 and above 10
90 and above 8
100 and above 0

Answer 1

Answer:

Mean Marks of Student is 51.75.

Step-by-step explanation:

First we convert the marks in class intervals and Cumulative frequency in frequency

We make class intervals with class length = 10

First interval is 0 - 10, then 10- 20, so on till 100 - 110.

Now we find class mark of every class interval,

formula for class mark,

$Class\:mark=\frac{Upper\:limit+Lower\:limit}{2}$

eg: class mark for interval 0 - 10 = $\frac{10+0}{2}$ = 5

     class mark for interval 10 - 20 = $\frac{20+10}{2}$ = 15 ...

Formula to calculate mean,

$Mean, \overline{x}=\frac{\sum_{i=0}^{n}f_ix_i}{\sum_{i=0}^{n}f_i}$

Now from Table (Attached)

$Mean, \overline{x}=\frac{4140}{80}\\\\\overline{x}=51.75$

Therefore, Mean Marks of Student is 51.75.

Answer 2

Answer:

Mean Marks of Student is 51.75.

Step-by-step explanation:

First we convert the marks in class intervals and Cumulative frequency in frequency

We make class intervals with class length = 10

First interval is 0 - 10, then 10- 20, so on till 100 - 110.

Now we find class mark of every class interval,

formula for class mark,

eg: class mark for interval 0 - 10 =  = 5

    class mark for interval 10 - 20 =  = 15 ...

Formula to calculate mean,

Now from Table (Attached)

Therefore, Mean Marks of Student is 51.75.