In: Statistics and Probability
The table below shows the scores of a group of students on a
10-point quiz.
Test ScoreFrequency
3 4
4 3
5 3
6 2
7 1
8 1
9 1
10 6
The mean score on this test is:
The median score on this test is
Solution:
Part a) The mean score on this test is:_______?
Formula:
xi: Test Score | fi: frequency | xi * fi |
3 | 4 | 12 |
4 | 3 | 12 |
5 | 3 | 15 |
6 | 2 | 12 |
7 | 1 | 7 |
8 | 1 | 8 |
9 | 1 | 9 |
10 | 6 | 60 |
Thus
Part b) The median score on this test is_________?
Find CF = Cumulative Frequencies for given frequency distribution.
To find CF , we add frequencies from top to bottom.
xi: Test Score | fi: frequency | CF: Cumulative Frequencies |
---|---|---|
3 | 4 | 4 |
4 | 3 | 7 |
5 | 3 | 10 |
6 | 2 | 12 |
7 | 1 | 13 |
8 | 1 | 14 |
9 | 1 | 15 |
10 | 6 | 21 |
N = 21 |
Find N / 2 = 21 / 2 = 10.5
Find CF such that:
CF
N/2 for first time
that is
CF
10.5
From table we have: CF =12 > 10.5 for first time.
Thus corresponding x value = 6 is the median.
Thus median = 6