Page 188 - Mathematics Coursebook

19.3 Drawing conclusions

19.3 Drawing conclusions

You can use pictograms, bar charts, bar line graphs, frequency diagrams and pie charts to compare two
sets of data.

When you are asked to compare two sets of data, follow these steps.

1 Look at the overall total number of items in each graph or chart and see if there is a big di$erence in
the totals.

2 Compare the shapes of the graphs or charts and comment on how they are di$erent.

Worked example 19.3

The pictograms show the number of people using a swimming pool during the fi rst week in January and
the fi rst week in July.
First week in January First week in July
Monday Monday
Tuesday Tuesday
Wednesday Wednesday
Thursday Thursday
Friday Friday
Key: represents 10 people Key: represents 10 people

a Compare the pictograms and make two comments.
b On which day of the week were twice as many people using the pool in the fi rst week of July than in
the fi rst week of January?
c No one used the pool on the Thursday in the fi rst week of January. Give a reason why you think this
might have happened.
a 1 More people used the pool in the fi rst week 1 You can see that there are a lot more pictures
in July than the fi rst week in January. in the July pictogram than the January pictogram.
2 In January most of the people used the pool 2 The January pictogram has more pictures
in the fi rst three days of the week, but in July at the start of the week, whereas the July
most of the people used the pool in the last pictogram has more pictures at the end of the
three days of the week. week.
b Wednesday In the fi rst week of January 40 people used the
pool and in the fi rst week of July 80 people
used the pool.

c The pool might have been closed for repair, Think of any sensible reason why there were no
for cleaning or for a national holiday. people using the pool.

19 Interpreting and discussing results 187