1. Calculate Class and their frequency table from the following grouped data

X	Cumulative Frequency
20	480
25	370
30	200
35	120
40	75
45	35

Solution:
First we convert Cumulative frequency table to gropued frequency table

>	Cumulative Frequency
> 20	480
> 25	370
> 30	200
> 35	120
> 40	75
> 45	35

Class and their frequency table is

Class	Cumulative Frequency	Frequency
20 - 25	480	110 (= 480 - 370)
25 - 30	370	170 (= 370 - 200)
30 - 35	200	80 (= 200 - 120)
35 - 40	120	45 (= 120 - 75)
40 - 45	75	40 (= 75 - 35)
45 - 50	35	35 (= 35)

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2. Calculate Class and their frequency table

X	Cumulative Frequency
10	88
20	73
30	48
40	28
50	16
60	8
70	3

Solution:
First we convert Cumulative frequency table to gropued frequency table

>	Cumulative Frequency
> 10	88
> 20	73
> 30	48
> 40	28
> 50	16
> 60	8
> 70	3

Class and their frequency table is

Class	Cumulative Frequency	Frequency
10 - 20	88	15 (= 88 - 73)
20 - 30	73	25 (= 73 - 48)
30 - 40	48	20 (= 48 - 28)
40 - 50	28	12 (= 28 - 16)
50 - 60	16	8 (= 16 - 8)
60 - 70	8	5 (= 8 - 3)
70 - 80	3	3 (= 3)

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