Question

65 POINTS!!! Amy works at the Apple Store at a commission rate of 3%. Ipads are 18% off on Mac Mondays. She helps a customer who buys, 2 Ipads originally priced at $499, and an iPhone priced at $575. If all purchases are made on Mac Monday and the sales tax rate is 8.875 What is the total amount the customer will pay?
Students answer- $575 + 499 + 499 = 1573 times 1.0875 = $1710.64

Identify the students mistake in the given answer. Then explain why the answer is incorrect and give the correct way to do it.

Answer 1

Answer:

1. The first mistake was in not taking 18% off the iPad price. A second mistake was in using an incorrect value for the sales tax multiplier. Those two mistakes together are why the answer is incorrect.
2. ($575 +0.82·2·499)·1.08875 = $1517.02

Step-by-step explanation:

iPads are 18% off on the day of purchase, so they should be charged at ...

   100% -18% = 82%

of full price. The sum shown includes two iPads at $499 each, without any discount. The total price is too high by $179.64.

The tax rate is given as 8.875%, so the multiplier on price will be ...

  100% +8.875% = 108.875% = 1.08875

The multiplier used by the student in the problem is 1.0875, so is too low.

_____

A correct computation could be written as ...

  ($575 + 2×499×0.82)×1.08875 ≈ $1517.02