OSA Classes Frequency, Consider the table below: Cumulative Midpoint, fm fm2 (Mass) f Frequency m (kg) 30.00 < 4 4 35.00 140 4900 40.00 40.00 < 11 B 45.00 495 22275 50.00 50.00 < A 43 55.00 1540 84700 60.00 60.00 < 17 80 60 C 1105 71825 70.00 60 The standard deviation is closest to: OA. 7.92 kg OB. 8.63 kg OC. 8.04 kg OD. 9.21 kg