1. Targeting Grade C GCSE Mathematics Handling Data
Unit 3 Interpreting Graphs

2. Interpret scatter diagrams
TOP: Practise interpreting different charts
Practice 1: What do scatter diagrams tell you?
Practice 2: How do you read a line graph?
Practice 3: How to compare box plots.
Practice 4: What do stem and leaf diagrams tell you?
TAIL
Can you:
Interpret scatter diagrams
Interpret line graphs
Compare box plots
Compare stem and leaf diagrams
Try a test
If not you need

3. TOP: Make two comments for each of the following charts. Also,
state which bar is the mode. 1)
Saturday
Sunday
Monday
Tuesday
The number of people who play golf are represented in this pictogram
Represents 20 golfers
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4. 2) The bar chart shows information about the favourite drink of each student in a class.
Lesson

5. Practice 1: Look at the following scatter diagrams
Practice 1: Look at the following scatter diagrams. Do they have positive or negative correlation and what does that mean?
1a) (b)
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6. 2) The table lists the weights of twelve books and the number of pages in each one.
On a copy of the grid, draw a scatter graph to show the information in the table.
Draw a line of best fit on the graph and then describe the correlation between the number of pages in the book and their weight.
Lesson

7. Practice 2: For the following line graph, answer the questions given.
1) Barry’s pulse rate is taken every 6 hours over 3 days. The graph shows his pulse rate in beats per minute.
Write down the first pulse rate shown on the graph.
Write down Barry’s highest pulse rate shown during the three days.
Work out the difference between his highest and lowest pulse rates shown on 3rd May.
Lesson

8. Practice 3: Compare the following box and whisker plots
Practice 3: Compare the following box and whisker plots. Remember to compare
the median (middle bar in the box) and the lower and upper quartiles (lower and
upper bars of the box), as well as the start and end points of the whiskers.
Remember:
Quartiles represent Quarters of the data – the lower quartile is ¼ of the data and is found ¼ of the way along the data set. The upper quartile is ¾ of the data and is found ¾ of the way along the data set. The median is ½ or 2/4 of the data.
Lesson

9. a) Find the median number of students late for school.
Practice 4: For the following stem and leaf diagram, answer the questions given.
Sherri recorded the number of students late for school each day for 21 days. The stem and leaf diagram shows this information.
a) Find the median number of students late for school.
b) Work out the range of the number of students who are late for school.
Lesson

10. TAIL Answers? Negative correlation
Joe has twelve cars for sale. The scatter diagram shows the ages and prices of the twelve cars. Describe the correlation between the age and price of these cars.
Answers?
Negative correlation
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11. Find (i) the lower quartile (ii) the upper quartile
2) Mary recorded the heights, in centimetres, of the girls in her class. She put the heights in order.
Find (i) the lower quartile
(ii) the upper quartile
b) On a copy of the grid, draw a box plot for this data.
Next for answers

12. Answers for Q2
Lower Quartile = 152
Upper Quartile = 177
Lesson