Question

Anthony and Miguel go to the store to purchase some

new DVDs. An advertisement in the window catches
their attention.
DVD
Deals!
3 for $22.50
5 for $37.50
Write your answers on another piece of paper. Show all of your work to
receive full credit.
Part A
Does the information on the sign represent a proportional relationship?
Explain how you know.
Part B
Miguel selects five DVDs to purchase. A few of the DVD cases appear to be
damaged, so the manager gives Miguel a 20% discount on his entire purchase.
Miguel tries to guess how much money will be deducted from the total cost.
What is a reasonable estimate of the cost of the DVDs before tax is added?
What is the actual cost before tax?
Part C
There is an 8% sales tax in the town where the store is located. What is Miguel's
total cost after sales tax has been added?
Part D
Anthony decided to buy two DVDs that were not included in the deal. His price
after tax was $21.60. What was the cost of the two DVDs before the sales tax was
added?
Chapter Review 18

Answer 1

Part A:

The information on the sign represents a proportional relationship. This can be determined by observing that as the number of DVDs purchased increases, the cost per DVD decreases. Specifically, the cost per DVD decreases as the number of DVDs purchased increases.

Part B:

A reasonable estimate of the cost of the DVDs before tax is added would be $37.50, since Miguel is purchasing 5 DVDs and that is the price advertised on the sign.

The actual cost before tax is $37.50 - (20/100)*$37.50 = $30.

Part C:

The total cost after sales tax has been added would be $30 + (8/100)*$30 = $32.40

Part D:

Anthony's price after tax was $21.60.

The cost of the two DVDs before the sales tax was added is $21.60 / (1+8/100) = $20.

Explanation: