2022 AMC 8 Problem 15

Below is the professionally curated solution for Problem 15 of the 2022 AMC 8, from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2022 AMC 8 solutions, or check the answer key.

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Concepts:data and graph interpretationslopeoptimization

Difficulty rating: 1140

15.

Laszlo went online to shop for black pepper and found thirty different black pepper options varying in weight and price, shown in the scatter plot below. In ounces, what is the weight of the pepper that offers the lowest price per ounce?

11

22

33

44

55

Solution:

For each weight, only the lowest-price point at that weight can give the lowest price per ounce.

At 11 ounce, the lowest price is more than 11 dollar, so the price per ounce is more than 11.

At 22 ounces, the lowest price is 22 dollars, so the price per ounce is 11.

At 33 ounces, the lowest price is about 2.52.5 dollars, so the price per ounce is about 2.53\frac{2.5}{3}, less than 11.

At 44 ounces, the lowest price is close to 3.93.9 dollars, so the price per ounce is close to 3.94\frac{3.9}{4}, still larger than the 33-ounce option.

At 55 ounces, the lowest price is close to 4.54.5 dollars, so the price per ounce is close to 4.55\frac{4.5}{5}, also larger than the 33-ounce option.

The price per ounce is lowest at 33 ounces.

Thus, the correct answer is C.

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