Question

The marks obtained by 40 students of a class are given below: 80, 10, 30, 70, 60, 50, 50, 40, 40, 20, 40, 90, 50, 30, 70, 10, 60, 50, 20, 70, 70, 30, 80, 40, 20, 80, 90, 50, 80, 60, 70, 40, 50, 60, 90, 60, 40, 40, 60 and 60.
How many students obtained marks below 40

Answer 1

Step 1: Arranging marks in ascending order
Given,
80, 10, 30, 70, 60, 50, 50, 40, 40, 20, 40, 90, 50, 30, 70, 10, 60, 50, 20, 70, 70, 30, 80, 40, 20, 80, 90, 50, 80, 60, 70, 40, 50, 60, 90, 60, 40, 40, 60 and 60.
Required ascending order:
10, 10, 20, 20, 20, 30, 30, 30, 40, 40, 40, 40, 40, 40, 40, 50, 50, 50, 50, 50, 50, 60, 60, 60, 60, 60, 60, 60, 70, 70, 70, 70, 70, 80, 80, 80, 80, 90, 90, 90.

Step 2: Constructing the frequency distribution table

Step 3: Calculating number of students that obtained marks below 40
From the frequency table we observe,
Students obtained marks below 40 are:
= Students having 10 marks + Students having 20 marks + Students having 30 marks
= 2 + 3 + 3 = 8 Students
Hence, there are 8 students who obtained below 40 marks.