Stage 12 · Data handling
Broken line graphs
Check the scale, then read each point.
How to do it
Method
Check the scale, then read each point
Thu 24°C, Fri 28°C: 28 − 24 = 4
Full working
28 − 24 = 4
In full
First see what each grid line on the side stands for, and where it starts (not always at 0); find the point and read across to the axis. A line going up means an increase, going down a decrease; the steeper it is, the bigger the change. How much it rose: the later point less the earlier: Thursday 24°C, Friday 28°C, 28 − 24 = 4, so it rose by 4°C. The highest less the lowest: find the highest and lowest points, then take one from the other.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
Highest temperature on Monday = ? °C
Show the answer and working
Answer: Highest temperature on Monday = 21 °C
Each grid line stands for 1: Monday's point is 7 lines above 14, 7 × 1 = 7, 14 + 7 = 21
Example 2
February to March: went up by $?
Show the answer and working
Answer: February to March: went up by $30
Each grid line stands for 10: February's point is on line 4, 4 × 10 = 40; March's point is on line 7, 7 × 10 = 70; 70 − 40 = 30
Example 3
Highest − lowest = ? cm
Show the answer and working
Answer: Highest − lowest = 8 cm
Each grid line stands for 2. Highest: week 4's point is on line 5, 5 × 2 = 10; lowest: week 1's point is on line 1, 1 × 2 = 2; 10 − 2 = 8
Example 4
Highest − lowest = $?
Show the answer and working
Answer: Highest − lowest = $120
Each grid line stands for 20. Highest: May's point is on line 7, 7 × 20 = 140; lowest: March's point is on line 1, 1 × 20 = 20; 140 − 20 = 120
Practise broken line graphs in the game →Stage 12 · Data handling · Free to start, unlimited questions, no download