Data Interpretation • Topic 4 of 5

Line Graphs

A line graph tracks a value over time; the slope shows the trend. Questions ask for the value at a point, the change or percent change between two points, the steepest rise/fall, or the average over the period. Read each point against the axis, and for percent change always divide by the earlier value.

✅ Solved examples

1. Visitors (in thousands): Jan 10, Feb 14, Mar 12, Apr 18. Total?
10+14+12+18 = 54 thousand.
2. Percent rise from Jan (10) to Apr (18)?
(18-10)/10 x 100 = 80%.
3. Average monthly visitors?
54/4 = 13.5 thousand.
4. Between which consecutive months was the rise largest?
Jan->Feb +4, Feb->Mar -2, Mar->Apr +6; largest rise Mar->Apr.

✏️ Practice — try these, take hints as needed

1. Points 8, 12, 10, 14. Total?
Add.
—
—
44
2. Percent change 8 to 12?
4/8.
x 100.
—
50%
3. Average of 8,12,10,14?
44/4.
—
—
11
4. Largest drop among 12->10 and 14->? (next 9)?
12->10 = -2, 14->9 = -5.
—
—
14 to 9 (drop 5)
5. Percent fall 14 to 7?
7/14.
x 100.
—
50%

📝 Topic test — 8 questions

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