4 The final examination results obtained by a group of 3200 Biology students are summarized on the cumulative frequency graph cumulative frequency 3500 3000 2500 2000 1500 1000 500 0 0 20 40 Examination result x Frequency 60 examination results 0 x 20 80 150 100 4a Find the median of the examination results 2 marks 3 marks 4b Find the interquartile range 4c The grouped frequency table below summarizes the examination results of this group 2 marks of students Write down the modal class 1100 40 x 60 20 x 40 350 x 4d Write down the mid interval value of the modal class loto an estimate of the mean examination result 60 x 80 1400 80 x 100 ctions Th e followin 200 tC 1 mark 2 marks