Biology · Grades 10–12
Population estimate from supplied records
Use supplied records only. Assume a closed population, equal capture probability, mixing and retained marks. The estimate has sampling uncertainty.
Rule and assumptions
Use supplied records only. Assume a closed population, equal capture probability, mixing and retained marks. The estimate has sampling uncertainty.
N ≈ MC/R
Worked examples
Supplied fictional records give M = 69 initially marked, C = 45 in a later sample, and R = 32 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.
N ≈ MC/R 69 × 45/32 = 97.031
97.031
Supplied fictional records give M = 58 initially marked, C = 77 in a later sample, and R = 56 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.
N ≈ MC/R 58 × 77/56 = 79.75
79.75
Try two questions
Supplied fictional records give M = 54 initially marked, C = 26 in a later sample, and R = 25 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.
Supplied fictional records give M = 73 initially marked, C = 29 in a later sample, and R = 29 marked in that sample. Use N ≈ MC/R under the stated assumptions. No animals are to be handled. Round to 3 decimal places if needed.
Answers and reasoning
Answers and marking notes
- 56.16
N ≈ MC/R 54 × 26/25 = 56.16
- 73
N ≈ MC/R 73 × 29/29 = 73
Further reading and review references
These are reference links, not copied exercises, institutional endorsement or proof of independent review.
Learning preview · independent educational and translation review required. Suggested grades are not official curriculum alignment.