Interpret trends and misleading broken-line graphs
Identify the interval of greatest change on a broken-line graph, and recognize how an axis that doesn't start at zero can make a change look bigger than it really is. Unlimited questions, five difficulty levels, and a full worked solution every time — free.
Try one
The broken-line graph below shows the temperature (in deg C). During which interval did the value change the most?
8 a.m.: 14° C
10 a.m.: 13° C
12 p.m.: 15° C
2 p.m.: 14° C
4 p.m.: 6° C
- 10 a.m. to 12 p.m.
- 2 p.m. to 4 p.m.
- 8 a.m. to 10 a.m.
- 12 p.m. to 2 p.m.
Answer: 2 p.m. to 4 p.m.
See one solved, step by step
A broken-line graph shows a runner's heart rate rising from 26 bpm to 29 bpm. The graph's vertical axis starts at 17 bpm instead of 0. What is true about this graph?
- The choice of where the axis starts has no effect on how the change looks.
- The graph is invalid because line graphs cannot show a runner's heart rate.
- A small rise always means the data was measured incorrectly.
- Starting the vertical axis at 17 instead of 0 makes the rise from 26 to 29 bpm look much bigger than it really is.
📘 Worked solution
1Real change: 29 - 26 = 3 bpmWork out the actual size of the increase.
2Axis starts at 17, not 0.Because the axis doesn't start at zero, that same 3 bpm change fills most of the graph's height, making it look dramatic.
3Answer: the graph exaggerates the change.A graph is misleading when its scale makes a small difference look large.
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