Week 3, lab

Introduction to Linear Functions: Percent Increase and Decrease expressed as rates of change.

Generally, people tip 15%, 18%, and 20% for meals. 

The tip is a percent of the amount of the bill.

The total bill after tip is a “percent increase” of the original bill.

Part 1 (2 ways of calculating percent increase)

1)	Download the spreadsheet from the course website.  Column A lists the price of bills from $5 to $100 in increments of $5.  Use the spreadsheet to calculate the amount for a 15% tip.  
2)	In column F calculate the total price of the bill by multiplying the bill by 15% and then adding the price of the bill.  
3)	In column J calculate the total price of the bill by multiplying by 115%. 
4)	Explain why column F has the same values as column J.
5)	If time remains, repeat this process for an 18% tip on a different worksheet.
6)	How could this method be applied to percent decrease?

Part 2, Linear functions and rate of change (slope)

1)	Copy and paste the values in column B and C into Graphit activity (do not include the header) and click plot.
2)	Provide 3 different observations about the graph.
3)	Describe how the graph is changing.

4)	Pick two different points off the graph.

5)	Using the points from # 5, subtract the two values that represent the tip.  

6)	Using the same two points, subtract the two values that represent the cost.

7)	What is the ratio of #6 to #7?

8)	Repeat steps 5-8 with two different points.
9)	Repeat steps 5-8 with another two different points.
10)	Your values from 8, 9, and 10 should be the same.  What is that value?  Try to determine why this is the case.