# Year 7 and 8 Statistics

Image source

YEAR 7 Standards:

• Investigate, interpret and analyse graphs from authentic data
• Identify and investigate issues involving numerical data collected from primary and secondary sources
• Construct and compare a range of  data displays including stem-and-leaf plots and dot plots
• Calculate mean, median, mode and range for sets of data. Interpret these statistics in the context of data.
• Describe and interpret data displays using median, mean and range.

Resources for Year 7:

YEAR 8 Standards:

• Data representation and interpretation – Investigate techniques for collecting data, including census, sampling and observation
• Explore the practicalities and implications of obtaining data through sampling using a variety of investigative processes
• Explore the variation of means and proportions of random samples drawn from the same population
• Investigate the effect of individual data values, including outliers, on the mean and median

Resources for Year 8:

Supporting Australian Mathematics Project –

# Probability and Percentage increases and decreases

Following our assessment task yesterday it is clear that some students need to revise certain areas of the work we have done in term 1 and 2:

Probability – Relative frequency with ten questions to complete.

Percentages – How to convert fractions and percentages to a pie chart (360 degrees) with ten questions to complete.

Percentage increases and decreases – Worked examples and five problems to solve.

Stem and Leaf plotsWorked example and thirteen questions to solve.

Problem #1: You have a list of 7 numbers. The average of the numbers is 9. If you take away one of the numbers, the average of the numbers is 8. What number did you take away?

Problem #2: Martin has completed five Maths tests and received an average score of 80%. What is the highest average he could have after the next test?

Problem #3: A Year 7 class was asked “How many goals did you shoot at lunchtime?”. The lowest answer was 5 and the highest answer was 20. The total of all the answers was 60. What is the smallest number of students who could have been asked?

# Term 3: Statistics and Probability

This term we are starting a unit of work on data and statistics and the key words you need to understand are:

• data (qualitative and quantitative)
• discrete and continuous
• census (whole population) and survey (sample)
• mean
• median
• mode

The Australian Bureau of Statistics have a range of educational resources that will assist us to explore, represent and interpret data.

# Graphs and Data

Image created in Create-A_Graph

Last week you were working on a poster showing the results of a class survey in table and graphical form. This data is just a small sample of the school and state data. When governments and businesses want to plan for the future they need to know information about the whole population – for example, where roads, schools and hospitals need to be built. This information is obtained using a census. The national census is conducted every four years, when the Australian Bureau of Statistics asks every household to complete a survey.

Some of the data obtained in the 2011 census is recorded here. Choose one of the categories that you are interested in and create a graph of the data using “Create-A-Graph”. Email your graph to me and a copy to yourself.

# “Lies, Damn Lies and Statistics!”

Learning Intention: Students will understand that data can be displayed in various ways and they will be able to interpret different types of graphs, including bar graphs, pie charts, stem-and-leaf plots and scatter plots.

Success Criteria: Students will complete the following activites and be able to explain what the graphs tell us about the data collected.

The above quote, popularised by Mark Twain, refers to the ways that politicians can sometimes “manipulate the data” to suppport decision-making. The same data can often be used to support or disprove a theory, depending on the emphasis. Over the next couple of weeks we will use the data from the CensusAtSchool questionnaire to learn more about summary statistics and graphing. Some of the activities we will do are:

You can use the random data sampler to display the data relevant to each question.

# Surveys and Data

Image Source

While I am away next week (Wednesday, Thursday and Friday) you are required to complete a class survey. Choose a topic of interest (favourite AFL football team, favourite ice-cream flavour, favourite sport etc), with at least four options, plus “Other”.

• Tally your class results in a table.
• Convert the results to percentages (use a calculator for this if necessary)
• On a 100cm strip of paper, colour each section corresponding to the data collected. For example, if 10 out of 25 people voted for Essendon, colour 40cm of the strip in essendon colours.
• Tape the ends of the paper strip together and create a pie chart on A3 paper from the paper circle.
• Colour your pie chart carefully and give it a heading. Make sure you include a key to interpret the results.

Please also complete “Survey 2” by going to the tabs at the top of this post.

# Preparing for Potato Olympics!

Today was spent preparing our Olympians for competition – the final vital statistics were recorded and trainers completed a dossier of biographical information about their potatoes. Students have chosen the countries that their potatoes will compete for and found out about the event they are responsible for organising. We are using a wiki and Google Docs forms and spreadsheets to share our results of the events. Students will be required to answer the following questions:

• What are the mean heights, girths, masses and volumes of Hawkesdale potatoes and of St. Aloysius potatoes?
• What are the median heights, girths, masses and volumes of both school’s potatoes?
• What is the range of heights, girths, masses and volumes of both school’s potatoes?
• Who had the tallest, shortest, widest, narrowest, heaviest, lightest, biggest and smallest potatoes?

We hope to be able to do a Skype link-up with St. Aloysius this week, when we can celebate the results of our inaugural Potato Olympics!

# Welcome to Technomaths

This is an aerial picture of Hawkesdale P12 College captured from Google Earth, showing the prerimeter of our school stadium. If you go to the ‘tools’ tab and click ‘ruler’ you can select ‘line’ or ‘path’ , which highlights and measures between points you mark. You can measure in centimeters, meters and kilometers. This shows that the roof area of the stadium measures 25 m wide and 30m long.

What is the perimeter of the stadium roof?

What is the area of the stadium roof?

Each square metre of roof area catches 1mm (1 cubic cm) of rainfall. So, to work out how much rain the stadium roof will catch you need to multiply the roof area by the monthly or annual rainfall. Using the new Bureau of Meterology “Climate Data Online” website you can find out the monthly and annual rainfall in Hawkesdale since 1884. Using the summary statistics for all years, leave me a comment about how much rain you would expect to collect this month or this year, showing your working.