Question

@Hero
One more? :)
A biologist catches 46 fish in a pond, tags them, and then releases them back into the pond. On a later visit to the pond, the biologist catches 20 fish, of which 8 are tagged.


Which is the best estimate for the number of fish in the pond?

A. 66
B. 115
C. 368
D. 920

IDK how to do this one. Explain? :)

Answer 1

This tells me that the 46 she tagged represents 8/20 ths of the total amount of all fish
or 2/5ths of the total
46 = 2/5 x
x = 5/2 * 46 or about 2.5 times 46
I'd go with 115

Answer 2

@Hero Is it 115?

Answer 3

It is correct, but @BangkokGarrett should make sure you understand it.

Answer 4

My explanation of it would be a bit different though.

Answer 5

I don't. Can u explain @Hero ?

Answer 6

It is a little confusing. She tags the fish. They then swim around and get all mixed up, right?
So when she finds that 8 of a random sample of 20 are tagged...that tells her that 8/20 (that's 40%) of the fish are tagged
So the question boils down to 46 is 40% of what number.

Answer 7

Tag 46 fish and let em go.
Do an experiment to figure out what % of the fish are tagged.
The experiment tells us 8/20ths or 40%...are now tagged
46 represents 40% of all the fish.
46 is 40% of what?
Use your favorite method to answer that.

Answer 8

Feel free to ask questions about the parts you don't understand

Answer 9

I have a different approach to this. I will post it soon. It is a more intuitive approach.

Answer 10

I GOT A 100!! THANKS GUYS!! :) Though I would still like to know how you do it @Hero

Answer 11

You're welcome