Lesson

Can you read information from Â dot plotsÂ ?

The following dot plot shows the number of students in each section of the school band:

a

Which section has the least members?

A

Percurssion

B

Woodwind

C

Brass

D

Strings

Worked Solution

b

How many people are in the band?

Worked Solution

c

How many more people are there in the Strings section than the Brass section?

Worked Solution

Idea summary

Dot plots show us how many of something, using dots. The key is really important, because it tells us if each dot is worth 1, or more than 1.

This video uses a number of column graph examples and explores some strategies about how to interpret them.

This table shows the number of badges five students sold for a local charity.

Students | Number of badges |
---|---|

\text{Derek} | 70 |

\text{William} | 65 |

\text{Frank} | 75 |

\text{Sandy} | 60 |

\text{Tara} | 65 |

a

Create a column graph which shows the number of badges by student.

Worked Solution

b

Which student sold the same number of badges as Tara?

A

Frank

B

Derek

C

William

Worked Solution

Idea summary

When drawing a column graph, the tick for the category should be in the center of the column. Each column should be the same width. There should be gaps between each column.

The height of the column is equal to the number of times that category occurs.

This video introduces horizontal bar graphs as an avenue for displaying and interpreting data.

The bar graph shows the merit points received by four students in a class.

a

How many points in total were earned by Tari and Emily?

Worked Solution

b

How many more points did Nayan earn than Ivan?

Worked Solution

Idea summary

A horizontal bar graph works in a similar way to a vertical bar graph, but the axes are switched around. The category is on the left axis, and the results are on the bottom axis. Instead of seeing how tall a bar is, we look at how far to the right the bar extends.

This video shows how side by side column graphs can be used to compare two sets of similar data.

A survey was conducted about people's favourite movie genre. The results were plotted in the column graph below.

a

Complete the frequency table with the information.

Comedy | Action | Drama | Horror | |
---|---|---|---|---|

Women | 30 | 5 | ||

Men | 40 | 20 |

Worked Solution

b

Which genre had the same number of men and women select it as their favourite?

Worked Solution

Idea summary

Column graphs can be vertical or horizontal, but we can also use side-by-side graphs to dig a little deeper into our data. Instead of showing a total, we can split it into categories to compare data.