Data Spread Review Worksheet
Statistics Practice & Review
Data Spread Review
Name:
Date: Period:
TEKS S(3)(D) | Describe and model variability in data distributions using quartiles, IQR, and sampling representations.
1
A marine biologist records the number of loggerhead sea turtle nests documented along 21 different protected coastal beaches during a single nesting season. The raw observation counts are displayed below:
74
147
54
85
102
96
105
89
65
61
70
126
131
108
172
58
122
114
82
138
76
Part A — Organize Data in Ascending Order 21 data values
1
2
3
4
5
6
7
8
9
10
11 (M)
12
13
14
15
16
17
18
19
20
21
Part B — Determine Key Cutoffs
Median (\(Q_2\)) [11th value]:
First Quartile (\(Q_1\)): Median of bottom 10 values
Third Quartile (\(Q_3\)): Median of top 10 values
Part C — Calculate Interquartile Range
Formula: \(\text{IQR} = Q_3 - Q_1\)
Show substitution & subtraction:
Final IQR:
Part D — Practical Interpretation & Outlier Check
In 1–2 complete sentences, describe what this IQR value tells the marine conservation team about the variability of sea turtle nesting counts across the middle 50% of the beaches:
Outlier Boundaries (\(1.5 \times \text{IQR}\) Criterion): \(1.5 \times \text{IQR} = \underline{\hspace{40px}}\)
Lower Fence: \(Q_1 - 1.5(\text{IQR}) =\)
Upper Fence: \(Q_3 + 1.5(\text{IQR}) =\)
Are there any outliers in this dataset? No Yes (Specify: )
High School Statistics • Describing Variability (IQR) TEKS S(3)(D) Review Task
