Following are the marks obtained by 25 students of class XI in an exam. Find out range and coefficient of range of the marks.

Marks 5−9 10−14 15−19 20−24 25−29 30−34

No. Students 4 6 3 2 6 4

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Solution

In order to calculate range and its coefficient, we must first convert the given inclusive class intervals in exclusive class intervals.

Class Interval Exclusive Class Interval Frequency

5 − 9
10 −14
15 −19
20 −24
25 −29
30− 34 4.5 − 9.5
9.5 − 14.5
14.5 − 19.5
19.5 − 24.5
24.5 − 29.5
29.5 − 34.5
4
6
3
2
6
4

$Range = Upper Limit of the Highest Class Interval - Lower Limit of the Lowest Class Interval or, Range = 34.5 - 4.5 = 30$

$Coefficient of Range = \frac{H - L}{H + L} = \frac{34.5 - 4.5}{34.5 + 4.5} = \frac{30}{39} = 0.769$

Suggest Corrections

Marks	10−20	20−30	30−40	40−50	50−60
No. of students	12	18	14	63	19

Marks	10−20	20−30	30−40	40−50	50−60	60−70	70−80	80−90	90−100
Number of Students	4	10	16	22	20	18	8	2	5

Marks	0−9	10−19	20−29	30−39	40−49	50−59
No. of Students	3	7	15	25	10	4

Marks	5−9	10−14	15−19	20−24	25−29	30−34
No. Students	4	6	3	2	6	4

Class Interval	Exclusive Class Interval	Frequency
5 − 9 10 −14 15 −19 20 −24 25 −29 30− 34	4.5 − 9.5 9.5 − 14.5 14.5 − 19.5 19.5 − 24.5 24.5 − 29.5 29.5 − 34.5	4 6 3 2 6 4