Answer:
[tex]Median = 15.80[/tex]
[tex]Mode = 15.20\ \&\ 15.25[/tex]
[tex]IQR = 2.35[/tex]
Step-by-step explanation:
Given
[tex]15.60,\ 18.75,\ 14.60,\ 15.80,\ 14.35,[/tex]
[tex]13.90,\ 17.50,\ 17.55,\ 13.80,\ 14.20,[/tex]
[tex]19.05,\ 15.35,\ 15.20,\ 19.45,\ 15.95,[/tex]
[tex]16.50,\ 16.30,\ 15.25,\ 15.05,\ 19.10,[/tex]
[tex]15.20,\ 16.22,\ 17.75,\ 18.40,\ 15.25.[/tex]
Solving (a): The median and the mode
First, we sort the data.
[tex]13.80,\ 13.90,\ 14.20,\ 14.35,\ 14.60,\ 15.05,\ 15.20,\ 15.20,\ 15.25,\ 15.25,[/tex]
[tex]15.35,\ 15.60,\ 15.80,\ 15.95,\ 16.22,\ 16.30,\ 16.50,\ 17.50,\ 17.55,\ 17.75,[/tex]
[tex]18.40,\ 18.75,\ 19.05,\ 19.10,\ 19.45.[/tex]
The median position is:
[tex]Median = \frac{n + 1}{2}th[/tex]
[tex]Median = \frac{25 + 1}{2}[/tex]
[tex]Median = \frac{26}{2}[/tex]
[tex]Median = 13th[/tex]
The 13th item is: 15.80
Hence:
[tex]Median = 15.80[/tex]
The modes are:
[tex]Mode = 15.20\ \&\ 15.25[/tex] --- they both have frequency of 2 while others occur once
Solving (b): The interquartile range
This is calculated as:
[tex]IQR = Q_3 - Q_1[/tex]
Since the median is at the 13th position, Q1 is:
[tex]Q_1 = \frac{1 + 13}{2}th[/tex]
[tex]Q_1 = \frac{14}{2}th[/tex]
[tex]Q_1 = 7th[/tex]
The 7th item is: 15.20
[tex]Q_1 = 15.20[/tex]
Similarly, Q3 is:
[tex]Q_3 = \frac{13+n}{2}[/tex]
[tex]Q_3 = \frac{13+25}{2}[/tex]
[tex]Q_3 = \frac{38}{2}[/tex]
[tex]Q_3 = 19th[/tex]
The 7th item is: 17.55
So:
[tex]Q_3 = 17.55[/tex]
Hence,
[tex]IQR = 17.55 - 15.20[/tex]
[tex]IQR = 2.35[/tex]
