Question

Find the decile range and percentile range on the basis of following data :

x	0-10	10-20	20-30	30-40	40-50	50-60	60-70	70-80
f	3	9	8	5	7	5	7	6

Answer 1

Class (x)	Frequency (f)	Cumulative frequency
0-10	3	3
10-20	9	12
20-30	8	20
30-40	5	25
40-50	7	32
50-60	5	37
60-70	7	44
70-80	6	50
	N = 50

Calculation of decile range

9N/10 = (9 x 50)/10 = 45

Cumulative frequency equal to or exactly greater than 45 is 50 whose corresponding class is 70 - 80

Cumulative frequency exactly greater than 5 is 12, whose corresponding class is 12 - 20

Calculation of percentile range-

90N/100 = (90 x 50)/100 = 45

Cumulative frequency exactly greater than 45 is 50, whose corresponding class is 70 – 80

Cumulative frequency exactly greater than 5 is 12, whose corresponding class is 10-20

∴ Percentile range = 71.66 – 12.22 = 59.44

Thus Percentile range = 59.44