3. (a) The marks obtained by some candidates in an examination are
(i)
(ii)
28 35 41 47 62
70 81
59 60 61 62 70 80 68
67 68 69 70 78 57 66
74 76 77 78 54 64 73
90 94 51 64 72 83
88 90
Construct a grouped frequency table for the distribution using the intervals 20 - 29
39, 40-49 etc
What is the probability that a candidate chosen at random had 50 to 69 marks?