The following table shows the distribution of marks obtained by some students in an examination. Marks 0-9 10-19 20-29 30-39 40-49 50-59 60-69 70-79 80-89 9...

The following table shows the distribution of marks obtained by some students in an examination.

(a) Construct a cumulative frequency table for the distribution

(b) Draw an ogive for the distribution

(c) Use your graph in (b) to determine : (i) semi- interquartile range ; (ii) number of students who failed, if the pass mark for the examination is 37 ; (iii) probability that a student selected at random scored between 20% and 60%.