2023 AMC 8 Problem 5

Attempt Problem 5 of the 2023 AMC 8 below, then check your answer against the video solution and professionally curated solution from LIVE by Po-Shen Loh. You can also try the full timed exam, view all 2023 AMC 8 solutions, or check the answer key.

All problems are used with official legal permission of the Mathematical Association of America (MAA).

5.

A lake contains 250250 trout, along with a variety of other fish. When a marine biologist catches and releases a sample of 180180 fish from the lake, 3030 are identified as trout. Assume that the ratio of trout to the total number of fish is the same in both the sample and the lake. How many fish are there in the lake?
12501250
15001500
17501750
18001800
20002000
Answer: B
Concepts:ratio and proportion
Small hint:
The sample has 3030 trout out of 180180 fish
Big hint:
Trout are 16\frac16 of all fish in the lake
Video solution:
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Written solution:
Note that 30180=16.\dfrac{30}{180} = \dfrac{1}{6}. This means that a sixth of the fish in the lake are trout, or in other words, the total number of fish is 66 times the number of trout.
Therefore, there are 6⋅250=15006 \cdot 250 = 1500 fish in the lake.
Thus, B is the correct answer.
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