SOLUTION: A biologist catches and marks 20 perch from a lake. A week later she catches 50 fish, of which 12 are marked. Write the equation he can use to get a good estimate of the perch.

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Question 81346: A biologist catches and marks 20 perch from a lake. A week later she catches 50 fish, of which 12 are marked. Write the equation he can use to get a good estimate of the perch.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
A biologist catches and marks 20 perch from a lake. A week later she catches 50 fish, of which 12 are marked. Write the equation he can use to get a good estimate of the perch.
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Let "x" be the total number of perch in the lake.
Use a proportion:
total #/number caught = sample total/sample # caught
x/50= 50/12
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Cheers,
Stan H.