Suppose you are the purchasing manager for a company that manufactures scanners and other computer peripherals. Your vendor for scanner motors is now offering "quantity discounts" in the form of instant rebates and lower shipping charges as follows.
Quantity Net Price Rebate Shipping
1–500 motors $16 none $1.50
501–1,000 motors 16 $1.30 1.10
1,001–2,000 motors 16 1.90 0.80
(a)
Calculate the cost of the motors, including shipping charges, for each category (in $).
1–500 motors $
17.50

Correct: Your answer is correct.
501–1,000 motors $
15.80

Correct: Your answer is correct.
1,001–2,000 motors $
14.90

Correct: Your answer is correct.
(b)
If you usually purchase 400 motors per month, what percent would be saved per motor by ordering 800 every two months? Round to the nearest tenth of a percent.

Incorrect: Your answer is incorrect.
%
(c)
What percent would be saved per motor by ordering 1,200 every three months? Round to the nearest tenth of a percent.

Incorrect: Your answer is incorrect.
%
(d)
How much money (in $) can be saved in a year by purchasing the motors every three months instead of every month?
$