2014 AMC 12A Problem 8

Attempt Problem 8 of the 2014 AMC 12A below, then check your answer against the professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2014 AMC 12A solutions, or check the answer key.

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8.

A customer who intends to purchase an appliance has three coupons, only one of which may be used:

Coupon 1: 10%10\% off the listed price if the listed price is at least $50\$50

Coupon 2: $20\$20 off the listed price if the listed price is at least $100\$100

Coupon 3: 18%18\% off the amount by which the listed price exceeds $100\$100

For which of the following listed prices will coupon 1 offer a greater price reduction than either coupon 2 or coupon 3?

$179.95\$179.95

$199.95\$199.95

$219.95\$219.95

$239.95\$239.95

$259.95\$259.95

Answer: C
Concepts:inequalitypercentage
Difficulty rating: 1440
Solution:

For a price P>100,P\gt100, the reductions are P10,\dfrac{P}{10}, 20,20, and 18100(P100).\dfrac{18}{100}(P-100).

Coupon 1 beats coupon 2 when P10>20,\dfrac{P}{10}\gt20, that is P>200.P\gt200. Coupon 1 beats coupon 3 when P10>18100(P100),\dfrac{P}{10}\gt\dfrac{18}{100}(P-100), that is P<225.P\lt225.

The only listed price in (200,225)(200,225) is $219.95.\$219.95.

Thus, the correct answer is C.

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