Question

Suppose that a scientist captures 20 fiddler crabs in a small freshwater pond and marks them before releasing them back to the pond. The following week, the scientist returns and captures 30 fiddler crabs, six of which are marked. What is the estimated size of the fiddler crab population

Answer 1

100 fiddler crabs

Explanation:

If the 30 crabs are a representation of the entire population, then 6 marked crabs in a population of 30 would mean that

6 / 30 = 0.20 or 20%

20% of the entire crab population are marked. Since we know that a total of 20 fiddler crabs are marked in the pond then we can divide this number of marked crabs by 20% in decimal form to get the estimated total size of the fiddler crab population

20 / 0.20 = 100 fiddler crabs