The following table gives the marks obtained by 100 students in a class test
Marks 0-10 10-20 20-30 30-40 40-50 50-60
No.of student 12 18 27 20 17 6
Find the average (in years) per case reported

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Solution

Marks Class-Marks
$(x_{i})$
Frequency
$(f_{i})$
$f_{i} x_{i}$
0 - 10 5 12 60
10 - 20 15 18 270
20 - 30 25 18 270
20 -30 27 27 675
30 - 40 35 20 700
50 - 60 50 6 330
Total 100 2800
$¯ x = \frac{\sum_{i = l}^{k} f_{i} x_{i}}{\sum f_{i}} = \frac{2800}{100} = 28$

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Similar questions

Marks obtained	0-10	10-20	20-30	30-40	40-50	50-60	60-70
No. of students	$2$	$10$	$12$	$15$	$13$	$8$	$4$

Marks:	0−10	10−20	20−30	30−40	40−50	50−60	60−70	70−80	80−90	90−100
Frequency:	3	5	16	12	13	20	5	4	1	1

\begin{matrix} Mark & 0 - 10 & 10 - 20 & 20 - 30 & 30 - 40 & 40 - 50 & 50 - 60 & 60 - 70 & 70 - 80 No. of Students (Frequency): & 4 & 10 & 16 & 22 & 20 & 18 & 8 & 2 \end{matrix}

80

C.I.	0-10	10-20	20-30	30-40	40-50	50-60	60-70	70-80	80-90	90-100
Freq.	3	5	16	12	13	20	5	4	1	1

Obtained Marks	20-30	30-40	40-50	50-60	60-70	70-80
Number of students	5	9	8	12	13	3

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