Mode:
Mode is the value that appears most frequently. In this case, 21-25 appears most frequently (10 times). Therefore, the mode of the given data is 21-25.
Median:
Median is the middle value when the data is arranged in ascending order. In this case, the data can be arranged as:
2, 3, 8, 10, 10, 12, 23, 31
Since there are 9 values, the middle value is the 5th one. Therefore, the median of the given data is 10.
Quartile Deviation:
Quartile deviation (QD) is a measure of variability that is similar to standard deviation. It is calculated as half the difference between the upper quartile (Q3) and the lower quartile (Q1).
To find Q1 and Q3, we first need to find the median (Q2). We have already found that Q2 is 10.
Next, we find the lower quartile (Q1) and upper quartile (Q3).
Q1 is the median of the lower half of the data, which is:
2, 3, 8, 10
Therefore, Q1 is 3.
Q3 is the median of the upper half of the data, which is:
10, 12, 23, 31
Therefore, Q3 is 12.
Now we can calculate the quartile deviation:
QD = (Q3 - Q1) / 2
QD = (12 - 3) / 2
QD = 4.5