The marks obtained by 40 students in a mathematics test are grouped as follows:
Marks (out of 60): 0–10, 10–20, 20–30, 30–40, 40–50, 50–60
Number of students : 2, 5, 8, 12, 7, 6
Answer the following questions:
(i) Prepare the cumulative frequency table required for constructing a less–than cumulative frequency curve.
(ii) Draw the curve on a suitable scale.
(iii) Using the curve, estimate the median mark obtained by the class.