Question

The arithmetic mean of marks of the students for the given data is:

Marks	No. of students
0-10	12
10-20	18
20-30	27
30-40	20
40-50	17
50-60	60

1. 38
2. 48
3. 18
4. 28

Answer 1

Correct Answer - Option 1 : 38

Concept:

Mean of the classed Data:

\(\rm Mean =\dfrac{ \sum\limits_{i=1}^{i=n}f_i\overline x_i}{\sum\limits_{i=1}^{i=n}f_i}\), where n is the total number of class and f and x̅ are the frequency and mean of the class

Calculation:

Marks	Middle Value	Frequency
0 - 10	5	12
10 - 20	15	18
20 - 30	25	27
30 - 40	35	20
40 - 50	45	17
50 - 60	55	60

 

Mean = \(\dfrac{5\times12+15\times18+25\times27+35\times20+45\times17+55\times60}{12+18+27+20+17+60}\)

Mean = \(5770\over154\) = 37.467 ≈ 38