2.12 How to interpret cf and rf

Class	Frequency	Cumulative Frequency (cf)	Relative Frequency (rf)	Cumulative Relative Frequency (crf)
30-35	4	4	0.09	0.09
35-40	10	14	0.23	0.32
40-45	20	34	0.45	0.77
45-50	8	42	0.18	0.95
50-55	2	44	0.04	1
	n=44	n=44