The following table records the marks obtained by 80 students in a test.
MATHEMATICS · Multi-part · A Level · Mathematics · Data presentation and interpretation · Data presentation and interpretation
Problem
The following table records the marks obtained by 80 students in a test.
(a) Marks : Below 20 | 20 – 30 | 30 – 40 | 40 – 50 | 50 – 60 | 60 and above
Number of students : 6 | 12 | 20 | 18 | 14 | 10
(b) (i) Assume that the first and last classes are of the same width as the neighbouring class intervals. Find the class mark for every class.
(c) (ii) Using the class marks obtained, determine the mean mark of the class.
(d) (iii) Verify your answer by repeating the calculation after choosing 45 as an assumed central value and comment on the result obtained in parts (ii) and (iii).