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3.1 Determine the following for each set of data:
I. Range
II. Median
III. Lower quartile
IV. Upper quartile

a) [tex]$\begin{array}{lllllllll}10 & 7 & 9 & 5 & 8 & 7 & 13 & 3 & 2\end{array}$[/tex]

3.2 The data below shows the number of laptops sold by 15 sales agents during the last financial year:
[tex]$\begin{array}{lllllllllllllll}
43 & 48 & 62 & 52 & 46 & 90 & 58 & 37 & 48 & 73 & 84 & 68 & 54 & 34 & 78
\end{array}$[/tex]

a) Determine the median of the number of laptops sold.

b) Calculate the range of the data.

c) Calculate the interquartile range (IQR).

d) Draw a box and whisker diagram for the data.


Sagot :

Let's address each part of the question step-by-step.

### 3.1

#### a) [tex]$\{10, 7, 9, 5, 8, 7, 13, 3, 2\}$[/tex]

I. Range

The range of a dataset is the difference between the maximum and minimum values.

Given data: [tex]$\{10, 7, 9, 5, 8, 7, 13, 3, 2\}$[/tex]

Maximum value = 13
Minimum value = 2

Range = Maximum value - Minimum value = 13 - 2 = 11

II. Median

To find the median, arrange the values in ascending order and find the middle value.

Sorted data: [tex]$\{2, 3, 5, 7, 7, 8, 9, 10, 13\}$[/tex]

Number of data points = 9 (which is odd). The median is the middle value (5th value in this sorted list).

Median = 7

III. Lower Quartile (Q1) and V. Upper Quartile (Q3)

The lower quartile (Q1) is the 25th percentile and the upper quartile (Q3) is the 75th percentile.

The sorted data: [tex]$\{2, 3, 5, 7, 7, 8, 9, 10, 13\}$[/tex]

Use the positions to calculate Q1 and Q3:

For Q1 (25th percentile), find the value at 25% of 9 (total data points):
Position = 0.25 (9 + 1) = 2.5
Average of the 2nd and 3rd values in sorted data: Q1 = (3 + 5) / 2 = 5.0

For Q3 (75th percentile), find the value at 75% of 9 (total data points):
Position = 0.75
(9 + 1) = 7.5
Average of the 7th and 8th values in sorted data: Q3 = (9 + 10) / 2 = 9.0

### Summary of 3.1:
- Range: 11
- Median: 7
- Lower Quartile (Q1): 5.0
- Upper Quartile (Q3): 9.0

### 3.2

#### Data: [tex]$\{43, 48, 62, 52, 46, 90, 58, 37, 48, 73, 84, 68, 54, 34, 78\}$[/tex]

Median

To find the median, arrange the values in ascending order and find the middle value.

Sorted data: [tex]$\{34, 37, 43, 46, 48, 48, 52, 54, 58, 62, 68, 73, 78, 84, 90\}$[/tex]

Number of data points = 15 (which is odd). The median is the middle value (8th value in this sorted list).

Median = 54

Range

The range of a dataset is the difference between the maximum and minimum values.

Maximum value = 90
Minimum value = 34

Range = Maximum value - Minimum value = 90 - 34 = 56

Interquartile Range (IQR)

For Q1 (25th percentile) and Q3 (75th percentile), find the respective positions and values:

For Q1:
Position = 0.25 (15 + 1) = 4
Q1 (4th value in sorted data) = 46

For Q3:
Position = 0.75
(15 + 1) = 12
Q3 (12th value in sorted data) = 73.5

IQR = Q3 - Q1 = 73.5 - 46 = 23.5

Box and Whisker Diagram

To draw a box and whisker diagram, you need the five-number summary: minimum, Q1, median, Q3, and maximum.

Five-number summary for the data:
- Minimum: 34
- Q1: 46
- Median: 54
- Q3: 73.5
- Maximum: 90

The box extends from Q1 to Q3, with a line at the median. The "whiskers" extend from the minimum to Q1 and from Q3 to the maximum.

Box and Whisker Diagram:

```
34 46 54 73.5 90
|--------|========|========|--------|
```

This visual representation helps to understand the spread and distribution of the data.

### Summary of 3.2:
- Median: 54
- Range: 56
- Interquartile Range (IQR): 23.5

This completes the detailed step-by-step solution for the given question.