Problem-Solving and Data AnalysisMediumEstimating a population by capture and recapture
Problem-Solving and Data Analysis practice question
Researchers tagged 300 fish in a lake and released them. Later they caught a random sample of 80 fish, of which 12 were tagged. Based on the sample, about how many fish are in the lake?
Answer: 2000
The sample suggests 12/80 = 15% of the lake's fish are tagged, so 300 is 15% of the total: 300/0.15 = 2,000.
Common wrong answers
- If you answered 380
- 380 adds the tagged fish and the sample.
- If you answered 500
- 500 divides 300 by 0.6.
- If you answered 1200
- 1200 multiplies 300 by 4, using the sample's untagged count.
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