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5.015 Sampling methods

Interactive practice questions

Conservationists previously captured, tagged and released $400$400 whales in a sanctuary. Some time later a large number of whales were observed, and $34%$34% were found to be tagged. Estimate $n$n, the population of the whales in the sanctuary.

Round your answer to the nearest whole number if necessary.

Medium
2min

The capture recapture technique was used to estimate the population of cuttlefish. At the beginning of the year the number of cuttlefish caught, tagged and released was $210$210. When $700$700 cuttlefish were taken at the end of the year, $140$140 of them were found to be recaptured tagged ones.

Medium
2min

A researcher captures a sample of $400$400 fish in a river, tags them and then releases them. The following day he captures a sample of $1200$1200 fish, of which $100$100 have tags attached to them. Estimate $p$p, the number of fish in the river.

Medium
1min

A local council wanted to monitor the number of rabbits in the area. They used the capture-recapture technique to estimate the population of rabbits. $219$219 rabbits were caught, tagged and released. Later, $42$42 rabbits were caught at random. $15$15 of these $42$42 rabbits had been tagged.

Medium
2min
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Outcomes

ACMEM130

investigate the different kinds of samples; for example, systematic samples, self-selected samples, simple random samples

ACMEM132

identify the target population to be surveyed

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