## Monday, December 27, 2010

### Graphing & Extrapolating: How Many Licks Does it Take?

Last week, we started to find out How Many Licks Does it Take to Get to the Center of a Tootsie Roll Pop.  Last time largely focused on data collection, which is a great skill, but doesn't answer the question at hand.

Since we weren't able to complete enough licks to get our answer, we need to graph the data and then extrapolate to find the answer.  You can do this by hand or using Excel.

Here are the instructions for creating the graph on Excel*
Open a new excel worksheet

Label column A "Number of Licks"

Label column B "Mass"

Fill in number of licks, continuing by 10s until you reach 200 (yes, go to 200 even if you didn't get anywhere near that many licks done).

Fill in corresponding masses

Highlight the numerical data (don't include the column titles in your highlighting)

Go to Insert, then Chart

Click on XY Scatter, then click Next

Click Next

Enter a chart title (name of lab), the x-axis label (Number of Licks), and the y-axis label (Mass (g))

Click Next

Select the option to place the chart as a new sheet

Click Finish

Click on one of the points on the graph - all the points should be highlighted

Go to Chart, then Add trendline

Click Okay

Click on the legend and delete it

Double click on the numbers on the y-axis.

Click on Scale

Change Minimum to 0

Double click on the background of the graph

Set area to none

Print the graph

Draw a horizontal line at the value you had for the stick and wrapper

At the point where the line you drew hits the line on the graph, draw a vertical line to the x-axis.

Estimate the value for where the line hits the axis - that is the number of licks it would take to get to the center of a Tootsie Roll Pop

*I wrote these instructions using an older version of Excel, which is still what I have access to. If you use a newer version and find that some of the terminology needs to be changed, please let me know.  Also, please let me know if something is unclear or you just aren't sure about something and I'll do my best to help.