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.
Find how many students have marks equal to or more than 70?

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 Frequency distribution table of marks is:

Step 3: Calculating no. of students having marks equal to or more than 70
From the frequency table we observed that:
Students having marks equal to or more than 70
= Students having 70 marks + Students having 80 marks + Students having 90 marks
= 5 + 4 + 3 = 12
Hence, total 12 students have marks equal to or more than 70.