Question

Arron just paid $7.40 for a new pair of sunglasses. His father told him that prices were different 10 years ago. Then his grandfather told him that 20 years ago, prices were even better. Arron did some research and found that the prices did change, but not by much. Ten years ago, the average price for a generic pair of sunglasses was $6.80, and 20 years ago it was $6.20. 1) Describe a possible arithmetic relationship between the decade and the price in that decade. Represent the relationship with a table, an explicit formula, and a graph. Describe the characteristics of each. 2) Describe a possible geometric relationship between the decade and the price in that decade. Represent the relationship with a table, explicit formula, and a graph. Describe the characteristics of each.

Answer 1

Arron just paid $7.40 for a new pair of sunglasses.

The price of pair of sunglasses ten years ago was $6.80

The price of pair of sunglasses twenty years ago was $6.20

To get the price of pair of sunglasses a decade ago:

You take the current price which is $7.40,

you subtract ($7.40 - $6.80) = ($6.80 - $6.20) = $0.60

*NB : The common difference here is $0.60

So the price(P) of pair of sunglasses x decades ago is = $7.40 - $0.60x

P = $7.40 - $0.60x

Plotting the graph of Price(P) of a pair of sunglasses against number of decades (x) should be easy now right?