Data, Graphs, and Statistics
Data is information. Collecting it, organizing it, and displaying it clearly is a core math skill. We use different graph types depending on what story the data tells. Statistics like mean, median, mode, and range help summarize a set of numbers.
Key Concepts
Mean, Median, Mode, Range
Mean (average): add all values, divide by count. Median: the middle value when sorted. Mode: the most frequent value. Range: max − min. For the data set {4, 7, 7, 9, 13}: mean=8, median=7, mode=7, range=9. Each tells a different story about the data.
Bar Charts and Line Graphs
Bar charts compare categories (populations of cities, scores per subject). Line graphs show change over time (temperature over a week, sales per month). Always label axes with units. The scale on the y-axis can make data look more or less dramatic — watch for misleading graphs.
Stem-and-Leaf Plots and Box Plots
Stem-and-leaf shows every data value grouped by tens digit. A box plot shows the five-number summary: minimum, Q1 (25th percentile), median, Q3 (75th percentile), maximum. The box contains the middle 50% of data. These help compare distributions between groups.
🆕 Statistics Explorer
Enter a data set to see mean, median, mode, range, and a bar chart!
✅ Check Your Understanding
1. What is the mean of {2, 4, 6, 8}?
2. What does the median represent?
3. Which graph type best shows change over time?