Problem:
Randy bought a compact disc player and needed CD’s.
While shopping, he found that Bob’s Department store sells CD’s for $15.00 each.
Joe’s CD Club sells them for only $10 each, but has a $25 membership fee.
He decided to compare the costs for CD’s from the two stores using a table, a graph, and an equation.
1. Use the table, the graph, and the equation to determine where Randy should buy his CD’s.
Explain your reasoning.
2. Which representation - the description, the table, the graph, or the equation helps Randy the most in making the decision of where to buy CD’s?
Explain your thinking.
Table
|
# of CD’s |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
10 |
|
Bob’s |
15 |
30 |
45 |
60 |
75 |
90 |
105 |
120 |
135 |
150 |
|
Joe’s |
35 |
45 |
55 |
65 |
75 |
85 |
95 |
105 |
115 |
125 |
Graph
Equation
Bob’s: C = 15n, where C is cost and n is number of CD’s
Joe’s: C = 10n + 25, where C is cost and n is number of CD’s