The following partially-completed grouped frequency distribution table shows the marks obtained by 40 students in a Mathematics class test.
Class interval (marks): 0–10, 10–20, 20–30, 30–40, 40–50
Number of students: 3, 5, x, 7, 6
Answer the questions that follow.
(a) What is meant by (i) a class interval and (ii) the frequency of a class in a grouped frequency distribution?
(b) Using the information given, find the value of x and hence complete the frequency table.
(c) After completing the table, state the modal class of the distribution.