Group discussion
For each of the following pairs of variables, discuss the strength and direction of the correlation (if any):
- The floor space of an office and the number of desks that can fit
- The number of students on an field trip and the number of teachers supervising
- The number of text messages sent and the amount of prepaid credit remaining
- The distance driven by a car and the amount of fuel in the tank
- The height of a person and the number of hats they own
- A household electricity bill and the total income of the residents
- The amount of internet data and the age of the internet user
The average prices of an airline ticket on a particular route from the years 2001 to 2009 are shown in the table below:
Average airline ticket prices (2001 to 2009) |
Year |
2001 |
2002 |
2003 |
2004 |
2005 |
2006 |
2007 |
2008 |
2009 |
Price |
\$280 |
$180 |
$270 |
$260 |
$240 |
$190 |
$230 |
$220 |
$190 |
Display this data in a scatterplot using a spreadsheet tool. Then fit a trendline to the data and display the equation of the line.
Group discussion
- Is this trendline accurate? Give reasons for your answer and comment on any factors that might be affecting the data.
The next table includes the prices from 2010 to 2014:
Average airline ticket prices (2010 to 2014) |
Year |
2010 |
2011 |
2012 |
2013 |
2014 |
Price |
\$180 |
$170 |
$160 |
$155 |
$150 |
Plot this data on a separate graph, and display the equation of the trendline.
Group discussion
- How does this trendline compare to the one above?
- Use the equation of each line to predict the average price of an airline ticket in the year 2015. What do you see?